diff --git a/LOG b/LOG
index cdf637ecfd..a7cade8d3f 100644
--- a/LOG
+++ b/LOG
@@ -379,3 +379,9 @@
     externs.h, stats.c, thread.c, thread.h, csug/threads.stex,
     primvars.ms, thread.ms, release_notes.stex,
     date.ss, primdata.ss, prims.ss
+- added immutable strings, vectors, fxvector, bytevectors, and boxes
+    5_4.ss, 5_6.ss, bytevector.ss, cmacros.ss, cpnanopass.ss,
+    fasl.ss, library.ss, mkheader.ss, primdata.ss, prims.ss,
+    externs.h, types.h, alloc.c, fasl.c, gc.c, scheme.c,
+    5_5.ms, 5_6.ms, bytevector.ms, misc.ms, root-experr*, patch*,
+    objects.stex
diff --git a/c/alloc.c b/c/alloc.c
index 22dac6a172..b0b4eba9d7 100644
--- a/c/alloc.c
+++ b/c/alloc.c
@@ -491,7 +491,7 @@ ptr S_vector_in(s, g, n) ISPC s; IGEN g; iptr n; {
 
     if (n == 0) return S_G.null_vector;
 
-    if ((uptr)n >= most_positive_fixnum)
+    if ((uptr)n >= maximum_vector_length)
         S_error("", "invalid vector size request");
 
     d = size_vector(n);
@@ -507,7 +507,7 @@ ptr S_vector(n) iptr n; {
 
     if (n == 0) return S_G.null_vector;
 
-    if ((uptr)n >= most_positive_fixnum)
+    if ((uptr)n >= maximum_vector_length)
         S_error("", "invalid vector size request");
 
     tc = get_thread_context();
@@ -552,6 +552,34 @@ ptr S_bytevector(n) iptr n; {
     return p;
 }
 
+ptr S_null_immutable_vector() {
+  ptr v;
+  find_room(space_new, 0, type_typed_object, size_vector(0), v);
+  VECTTYPE(v) = (0 << vector_length_offset) | type_vector | vector_immutable_flag;
+  return v;
+}
+
+ptr S_null_immutable_fxvector() {
+  ptr v;
+  find_room(space_new, 0, type_typed_object, size_fxvector(0), v);
+  VECTTYPE(v) = (0 << fxvector_length_offset) | type_fxvector | fxvector_immutable_flag;
+  return v;
+}
+
+ptr S_null_immutable_bytevector() {
+  ptr v;
+  find_room(space_new, 0, type_typed_object, size_bytevector(0), v);
+  VECTTYPE(v) = (0 << bytevector_length_offset) | type_bytevector | bytevector_immutable_flag;
+  return v;
+}
+
+ptr S_null_immutable_string() {
+  ptr v;
+  find_room(space_new, 0, type_typed_object, size_string(0), v);
+  VECTTYPE(v) = (0 << string_length_offset) | type_string | string_immutable_flag;
+  return v;
+}
+
 ptr S_record(n) iptr n; {
     ptr tc = get_thread_context();
     ptr p;
diff --git a/c/externs.h b/c/externs.h
index 00026bbba0..58750cce6f 100644
--- a/c/externs.h
+++ b/c/externs.h
@@ -67,6 +67,10 @@ extern ptr S_vector_in PROTO((ISPC s, IGEN g, iptr n));
 extern ptr S_vector PROTO((iptr n));
 extern ptr S_fxvector PROTO((iptr n));
 extern ptr S_bytevector PROTO((iptr n));
+extern ptr S_null_immutable_vector PROTO((void));
+extern ptr S_null_immutable_fxvector PROTO((void));
+extern ptr S_null_immutable_bytevector PROTO((void));
+extern ptr S_null_immutable_string PROTO((void));
 extern ptr S_record PROTO((iptr n));
 extern ptr S_closure PROTO((ptr cod, iptr n));
 extern ptr S_mkcontinuation PROTO((ISPC s, IGEN g, ptr nuate, ptr stack,
diff --git a/c/fasl.c b/c/fasl.c
index ccc11c46bd..147ade5423 100644
--- a/c/fasl.c
+++ b/c/fasl.c
@@ -608,8 +608,11 @@ static void faslin(ptr tc, ptr *x, ptr t, ptr *pstrbuf, faslFile f) {
             return;
         }
         case fasl_type_box:
+        case fasl_type_immutable_box:
             *x = Sbox(FIX(0));
             faslin(tc, &INITBOXREF(*x), t, pstrbuf, f);
+            if (ty == fasl_type_immutable_box)
+              BOXTYPE(*x) = type_immutable_box;
             return;
         case fasl_type_symbol: {
             iptr n;
@@ -635,15 +638,23 @@ static void faslin(ptr tc, ptr *x, ptr t, ptr *pstrbuf, faslFile f) {
             faslin(tc, &EXACTNUM_IMAG_PART(*x), t, pstrbuf, f);
             return;
         case fasl_type_group:
-        case fasl_type_vector: {
+        case fasl_type_vector:
+        case fasl_type_immutable_vector: {
             iptr n; ptr *p;
             n = uptrin(f);
             *x = S_vector(n);
             p = &INITVECTIT(*x, 0);
             while (n--) faslin(tc, p++, t, pstrbuf, f);
+            if (ty == fasl_type_immutable_vector) {
+              if (Svector_length(*x) == 0)
+                *x = NULLIMMUTABLEVECTOR(tc);
+              else
+                Svector_set_immutable(*x);
+            }
             return;
         }
-        case fasl_type_fxvector: {
+        case fasl_type_fxvector:
+        case fasl_type_immutable_fxvector: {
             iptr n; ptr *p;
             n = uptrin(f);
             *x = S_fxvector(n);
@@ -653,13 +664,26 @@ static void faslin(ptr tc, ptr *x, ptr t, ptr *pstrbuf, faslFile f) {
               if (!FIXRANGE(t)) toolarge(f->uf->path);
               *p++ = FIX(t);
             }
+            if (ty == fasl_type_immutable_fxvector) {
+              if (Sfxvector_length(*x) == 0)
+                *x = NULLIMMUTABLEFXVECTOR(tc);
+              else
+                Sfxvector_set_immutable(*x);
+            }
             return;
         }
-        case fasl_type_bytevector: {
+        case fasl_type_bytevector:
+        case fasl_type_immutable_bytevector: {
             iptr n;
             n = uptrin(f);
             *x = S_bytevector(n);
             bytesin(&BVIT(*x,0), n, f);
+            if (ty == fasl_type_immutable_bytevector) {
+              if (Sbytevector_length(*x) == 0)
+                *x = NULLIMMUTABLEBYTEVECTOR(tc);
+              else
+                Sbytevector_set_immutable(*x);
+            }
             return;
         }
         case fasl_type_base_rtd: {
@@ -803,11 +827,18 @@ static void faslin(ptr tc, ptr *x, ptr t, ptr *pstrbuf, faslFile f) {
             *x = S_inexactnum(FLODAT(rp), FLODAT(ip));
             return;
         }
-        case fasl_type_string: {
+        case fasl_type_string:
+        case fasl_type_immutable_string: {
             iptr i, n; ptr str;
             n = uptrin(f);
             str = S_string((char *)0, n);
             for (i = 0; i != n; i += 1) Sstring_set(str, i, uptrin(f));
+            if (ty == fasl_type_immutable_string) {
+              if (n == 0)
+                str = NULLIMMUTABLESTRING(tc);
+              else
+                Sstring_set_immutable(str);
+            }
             *x = str;
             return;
         }
diff --git a/c/gc.c b/c/gc.c
index a6695d91bb..2db15e555b 100644
--- a/c/gc.c
+++ b/c/gc.c
@@ -267,7 +267,11 @@ static ptr copy(pp, pps) ptr pp; ISPC pps; {
           S_G.bytesof[tg][countof_vector] += n;
 #endif /* ENABLE_OBJECT_COUNTS */
         /* assumes vector lengths look like fixnums; if not, vectors will need their own space */
-          find_room(space_impure, tg, type_typed_object, n, p);
+          if (TYPE_IMMP(tf, vector_immutable_flag)) {
+            find_room(space_pure, tg, type_typed_object, n, p);
+          } else {
+            find_room(space_impure, tg, type_typed_object, n, p);
+          }
           copy_ptrs(type_typed_object, p, pp, n);
         /* pad if necessary */
           if ((len & 1) == 0) INITVECTIT(p, len) = FIX(0);
@@ -317,12 +321,12 @@ static ptr copy(pp, pps) ptr pp; ISPC pps; {
          * swept already.  NB: assuming keyvals are always pairs. */
           if (next != Sfalse && SPACE(keyval) & space_old)
             tlcs_to_rehash = S_cons_in(space_new, 0, p, tlcs_to_rehash);
-      } else if ((iptr)tf == type_box) {
+      } else if (TYPEP(tf, mask_box, type_box)) {
 #ifdef ENABLE_OBJECT_COUNTS
           S_G.countof[tg][countof_box] += 1;
 #endif /* ENABLE_OBJECT_COUNTS */
           find_room(space_impure, tg, type_typed_object, size_box, p);
-          BOXTYPE(p) = type_box;
+          BOXTYPE(p) = (iptr)tf;
           INITBOXREF(p) = Sunbox(pp);
       } else if ((iptr)tf == type_ratnum) {
         /* not recursive: place in space_data and relocate fields immediately */
@@ -555,7 +559,7 @@ static void sweep(ptr tc, ptr p, IBOOL sweep_pure) {
     if (sweep_pure || RECORDDESCMPM(RECORDINSTTYPE(p)) != FIX(0)) {
       sweep_record(p);
     }
-  } else if ((iptr)tf == type_box) {
+  } else if (TYPEP(tf, mask_box, type_box)) {
     relocate(&INITBOXREF(p))
   } else if ((iptr)tf == type_ratnum) {
     if (sweep_pure) {
@@ -1313,7 +1317,7 @@ static iptr size_object(p) ptr p; {
         return size_record_inst(UNFIX(RECORDDESCSIZE(tf)));
     } else if (TYPEP(tf, mask_fxvector, type_fxvector)) {
         return size_fxvector(Sfxvector_length(p));
-    } else if ((iptr)tf == type_box) {
+    } else if (TYPEP(tf, mask_box, type_box)) {
         return size_box;
     } else if ((iptr)tf == type_ratnum) {
         return size_ratnum;
@@ -1426,6 +1430,10 @@ static void sweep_thread(p) ptr p; {
     relocate(&TARGETMACHINE(tc))
     relocate(&FXLENGTHBV(tc))
     relocate(&FXFIRSTBITSETBV(tc))
+    relocate(&NULLIMMUTABLEVECTOR(tc))
+    relocate(&NULLIMMUTABLEFXVECTOR(tc))
+    relocate(&NULLIMMUTABLEBYTEVECTOR(tc))
+    relocate(&NULLIMMUTABLESTRING(tc))
     /* immediate METALEVEL */
     relocate(&COMPILEPROFILE(tc))
     /* immediate GENERATEINSPECTORINFORMATION */
diff --git a/c/scheme.c b/c/scheme.c
index c81fff48b7..b8d988a7d2 100644
--- a/c/scheme.c
+++ b/c/scheme.c
@@ -90,6 +90,11 @@ static void main_init() {
                  i & 0x10 ? 4 : i & 0x20 ? 5 : i & 0x40 ? 6 : i & 0x80 ? 7 : 0);
     }
 
+    NULLIMMUTABLEVECTOR(tc) = S_null_immutable_vector();
+    NULLIMMUTABLEFXVECTOR(tc) = S_null_immutable_fxvector();
+    NULLIMMUTABLEBYTEVECTOR(tc) = S_null_immutable_bytevector();
+    NULLIMMUTABLESTRING(tc) = S_null_immutable_string();
+
     PARAMETERS(tc) = S_G.null_vector;
     for (i = 0 ; i < virtual_register_count ; i += 1) {
       VIRTREG(tc, i) = FIX(0);
diff --git a/c/types.h b/c/types.h
index 8273478a34..6b824e67d6 100644
--- a/c/types.h
+++ b/c/types.h
@@ -235,6 +235,7 @@ typedef struct _bucket_pointer_list {
 #define UNFIX(x) Sfixnum_value(x)
 
 #define TYPEP(x,mask,type) (((iptr)(x) & (mask)) == (type))
+#define TYPE_IMMP(x,immutable_flag) ((iptr)(x) & (immutable_flag))
 
 /* reloc fields */
 #define RELOC_EXTENDED_FORMAT(x) ((x)&reloc_extended_format)
diff --git a/csug/objects.stex b/csug/objects.stex
index b9f3c0baa7..2beb3e0e74 100644
--- a/csug/objects.stex
+++ b/csug/objects.stex
@@ -540,6 +540,42 @@ s ;=> "$$$"
 \endschemedisplay
 
 
+%----------------------------------------------------------------------------
+\entryheader
+\formdef{mutable-string?}{\categoryprocedure}{(mutable-string? \var{obj})}
+\formdef{immutable-string?}{\categoryprocedure}{(immutable-string? \var{obj})}
+\returns \scheme{#t} if \var{obj} is a mutable/immutable string, \scheme{#f} otherwise
+\listlibraries
+\endentryheader
+
+\noindent
+String-mutation operations, such as \scheme{string-set!}, fail when given an immutable string.
+Strings are mutable by default, but \scheme{string->immutable-string}
+creates immutable strings.
+
+\schemedisplay
+(mutable-string? (string #\a #\b #\c)) ;=> #t
+(mutable-string? (string->immutable-string "abc")) ;=> #f
+(immutable-string? (string #\a #\b #\c)) ;=> #f
+(immutable-string? (string->immutable-string "abc")) ;=> #t
+\endschemedisplay
+
+%----------------------------------------------------------------------------
+\entryheader
+\formdef{string->immutable-string}{\categoryprocedure}{(string->immutable-string \var{string})}
+\returns either an immutable copy of \var{string} or \var{string} itself
+\listlibraries
+\endentryheader
+
+\noindent
+\var{string} must be a string. The result is \var{string} itself if \var{string}
+is immutable, otherwise the result is an immutable string with the same content as \var{string}.
+
+\schemedisplay
+(define s (string->string-immutable "xyz"))
+(string-set! s 0 #\a) ;=> \var{exception: "xyz" is immutable}
+\endschemedisplay
+
 
 \section{Vectors}
 
@@ -602,6 +638,43 @@ See also the description of fixnum-only vectors (fxvectors) below.
   v) ;=> #(1 2 73 4 5)
 \endschemedisplay
 
+%----------------------------------------------------------------------------
+\entryheader
+\formdef{mutable-vector?}{\categoryprocedure}{(mutable-vector? \var{obj})}
+\formdef{immutable-vector?}{\categoryprocedure}{(immutable-vector? \var{obj})}
+\returns \scheme{#t} if \var{obj} is a mutable/immutable vector, \scheme{#f} otherwise
+\listlibraries
+\endentryheader
+
+\noindent
+Vector-mutation operations, such as \scheme{vector-set!}, fail when given an immutable vector.
+Vectors are mutable by default, but \scheme{vector->immutable-vector}
+creates immutable vectors.
+
+\schemedisplay
+(mutable-vector? (vector 1 2 3)) ;=> #t
+(mutable-vector? (vector->immutable-vector (vector 1 2 3))) ;=> #f
+(immutable-vector? (vector 1 2 3)) ;=> #f
+(immutable-vector? (vector->immutable-vector (vector 1 2 3))) ;=> #t
+\endschemedisplay
+
+%----------------------------------------------------------------------------
+\entryheader
+\formdef{vector->immutable-vector}{\categoryprocedure}{(vector->immutable-vector \var{vector})}
+\returns either an immutable copy of \var{vector} or \var{vector} itself
+\listlibraries
+\endentryheader
+
+\noindent
+\var{vector} must be a vector. The result is \var{vector} itself if \var{vector}
+is immutable, otherwise the result is an immutable vector with the same content as \var{vector}.
+
+\schemedisplay
+(define s (vector->vector-immutable (vector 1 2 3)))
+(vector-set! s 0 0) ;=> \var{exception: \#(1 2 3) is immutable}
+\endschemedisplay
+
+    
 \section{Fixnum-Only Vectors\label{SECTFXVECTORS}}
 
 Fixnum-only vectors, or ``fxvectors,'' are like vectors but contain
@@ -795,6 +868,43 @@ as \var{fxvector}.
   (eq? v (fxvector-copy v))) ;=> #f
 \endschemedisplay
 
+%----------------------------------------------------------------------------
+\entryheader
+\formdef{mutable-fxvector?}{\categoryprocedure}{(mutable-fxvector? \var{obj})}
+\formdef{immutable-fxvector?}{\categoryprocedure}{(immutable-fxvector? \var{obj})}
+\returns \scheme{#t} if \var{obj} is a mutable/immutable fxvector, \scheme{#f} otherwise
+\listlibraries
+\endentryheader
+
+\noindent
+Fxvector-mutation operations, such as \scheme{fxvector-set!}, fail when given an immutable fxvector.
+Fxvectors are mutable by default, but \scheme{fxvector->immutable-fxvector}
+creates immutable fxvectors.
+
+\schemedisplay
+(mutable-fxvector? (fxvector 1 2 3)) ;=> #t
+(mutable-fxvector? (fxvector->immutable-fxvector (fxvector 1 2 3))) ;=> #f
+(immutable-fxvector? (fxvector 1 2 3)) ;=> #f
+(immutable-fxvector? (fxvector->immutable-fxvector (fxvector 1 2 3))) ;=> #t
+\endschemedisplay
+
+%----------------------------------------------------------------------------
+\entryheader
+\formdef{fxvector->immutable-fxvector}{\categoryprocedure}{(fxvector->immutable-fxvector \var{fxvector})}
+\returns either an immutable copy of \var{fxvector} or \var{fxvector} itself
+\listlibraries
+\endentryheader
+
+\noindent
+\var{fxvector} must be a fxvector. The result is \var{fxvector} itself if \var{fxvector}
+is immutable, otherwise the result is an immutable fxvector with the same content as \var{fxvector}.
+
+\schemedisplay
+(define s (fxvector->fxvector-immutable (fxvector 1 2 3)))
+(fxvector-set! s 0 0) ;=> \var{exception: \#vfx(1 2 3) is immutable}
+\endschemedisplay
+
+    
 \section{Bytevectors\label{SECTBYTEVECTORS}}
 
 As with vectors, {\ChezScheme} extends the syntax of bytevectors to allow
@@ -971,6 +1081,44 @@ These procedures store the given value in the 3, 5, 6, or 7 bytes starting
 at index \var{n} (zero-based) of \var{bytevector}.
 Negative values are stored as their two's complement equivalent.
 
+%----------------------------------------------------------------------------
+\entryheader
+\formdef{mutable-bytevector?}{\categoryprocedure}{(mutable-bytevector? \var{obj})}
+\formdef{immutable-bytevector?}{\categoryprocedure}{(immutable-bytevector? \var{obj})}
+\returns \scheme{#t} if \var{obj} is a mutable/immutable bytevector, \scheme{#f} otherwise
+\listlibraries
+\endentryheader
+
+\noindent
+Bytevector-mutation operations, such as \scheme{bytevector-set!}, fail when given an immutable bytevector.
+Bytevectors are mutable by default, but \scheme{bytevector->immutable-bytevector}
+creates immutable bytevectors.
+
+\schemedisplay
+(mutable-bytevector? (bytevector 1 2 3)) ;=> #t
+(mutable-bytevector?
+ (bytevector->immutable-bytevector (bytevector 1 2 3))) ;=> #f
+(immutable-bytevector? (bytevector 1 2 3)) ;=> #f
+(immutable-bytevector?
+ (bytevector->immutable-bytevector (bytevector 1 2 3))) ;=> #t
+\endschemedisplay
+
+%----------------------------------------------------------------------------
+\entryheader
+\formdef{bytevector->immutable-bytevector}{\categoryprocedure}{(bytevector->immutable-bytevector \var{bytevector})}
+\returns either an immutable copy of \var{bytevector} or \var{bytevector} itself
+\listlibraries
+\endentryheader
+
+\noindent
+\var{bytevector} must be a bytevector. The result is \var{bytevector} itself if \var{bytevector}
+is immutable, otherwise the result is an immutable bytevector with the same content as \var{bytevector}.
+
+\schemedisplay
+(define s (bytevector->bytevector-immutable (bytevector 1 2 3)))
+(bytevector-set! s 0 0) ;=> \var{exception: \#vu8(1 2 3) is immutable}
+\endschemedisplay
+
 
 \section{Boxes\label{SECTBOXES}}
 
@@ -1054,6 +1202,42 @@ recently.
     (unbox b))) ;=> 4
 \endschemedisplay
 
+%----------------------------------------------------------------------------
+\entryheader
+\formdef{mutable-box?}{\categoryprocedure}{(mutable-box? \var{obj})}
+\formdef{immutable-box?}{\categoryprocedure}{(immutable-box? \var{obj})}
+\returns \scheme{#t} if \var{obj} is a mutable/immutable box, \scheme{#f} otherwise
+\listlibraries
+\endentryheader
+
+\noindent
+Box-mutation operations, such as \scheme{set-box!}, fail when given an immutable box.
+Boxes are mutable by default, but \scheme{box-immutable}
+creates immutable boxes.
+
+\schemedisplay
+(box-mutable? (box 1)) ;=> #t
+(box-mutable? (box-immutable 1) ;=> #f
+(box-immutable? (box 1)) ;=> #f
+(box-immutable? (box-immutable 1) ;=> #t
+\endschemedisplay
+
+%----------------------------------------------------------------------------
+\entryheader
+\formdef{box-immutable}{\categoryprocedure}{(box-immutable \var{obj})}
+\returns a new immutable box containing \var{obj}
+\listlibraries
+\endentryheader
+
+\noindent
+Since boxes are intended to support a mutable level of indirection, imutable boxes
+are rarely useful, but they are provided for consistency with vectors.
+
+\schemedisplay
+(define s (box-immutable 1))
+(set-box! s 0) ;=> \var{exception: \#\&1 is immutable}
+\endschemedisplay
+
 
 \section{Symbols\label{SECTMISCSYMBOLS}}
 
diff --git a/mats/5_5.ms b/mats/5_5.ms
index b59c966c95..b44f042348 100644
--- a/mats/5_5.ms
+++ b/mats/5_5.ms
@@ -731,3 +731,33 @@
     (equal? (string->list "abc") '(#\a #\b #\c))
     (equal? (string->list "") '())
  )
+
+(mat string->immutable-string
+    (begin
+      (define immutable-abc-string
+        (string->immutable-string (string #\a #\b #\c)))
+      #t)
+
+    (immutable-string? immutable-abc-string)
+    (not (mutable-string? immutable-abc-string))
+    
+    (equal? "abc" immutable-abc-string)
+    (eq? immutable-abc-string
+         (string->immutable-string immutable-abc-string))
+    
+    (not (immutable-string? (make-string 5)))
+    (mutable-string? (make-string 5))
+    
+    (immutable-string? (string->immutable-string (string)))
+    (not (mutable-string? (string->immutable-string (string))))
+    (not (immutable-string? (string)))
+    (mutable-string? (string))
+    
+    (not (immutable-string? (string-copy immutable-abc-string)))
+
+    (error? (string-set! immutable-abc-string 0 #\a))
+    (error? (string-fill! immutable-abc-string #\a))
+    (error? (substring-fill! immutable-abc-string 0 1 #\a))
+    (error? (string-copy! "xyz" 0 immutable-abc-string 0 3))
+    (error? (string-truncate! immutable-abc-string 1))
+)
diff --git a/mats/5_6.ms b/mats/5_6.ms
index bc3302752f..17334bba44 100644
--- a/mats/5_6.ms
+++ b/mats/5_6.ms
@@ -1132,3 +1132,61 @@
                 (errorf #f "failed")))))))
     (make-string 200 #\.))
 )
+
+(mat vector->immutable-vector
+    (begin
+      (define immutable-123-vector
+        (vector->immutable-vector (vector 1 2 3)))
+      #t)
+    
+    (immutable-vector? immutable-123-vector)
+    (not (mutable-vector? immutable-123-vector))
+    
+    (equal? '#(1 2 3) immutable-123-vector)
+    (eq? immutable-123-vector
+         (vector->immutable-vector immutable-123-vector))
+    
+    (mutable-vector? (make-vector 5))
+    (not (immutable-vector? (make-vector 5)))
+    
+    (immutable-vector? (vector->immutable-vector (vector)))
+    (not (mutable-vector? (vector->immutable-vector (vector))))
+    (not (immutable-vector? (vector)))
+    (mutable-vector? (vector))
+    
+    (not (immutable-vector? (vector-copy immutable-123-vector)))
+
+    (error? (vector-set! immutable-123-vector 0 1))
+    (error? (vector-set-fixnum! immutable-123-vector 0 1))
+    (error? (vector-fill! immutable-123-vector 0))
+    (error? (vector-sort! < immutable-123-vector))
+)
+
+
+
+(mat fxvector->immutable-fxvector
+    (begin
+      (define immutable-123-fxvector
+        (fxvector->immutable-fxvector (fxvector 1 2 3)))
+      #t)
+    
+    (immutable-fxvector? immutable-123-fxvector)
+    (not (mutable-fxvector? immutable-123-fxvector))
+    
+    (equal? '#vfx(1 2 3) immutable-123-fxvector)
+    (eq? immutable-123-fxvector
+         (fxvector->immutable-fxvector immutable-123-fxvector))
+    
+    (mutable-fxvector? (make-fxvector 5))
+    (not (immutable-fxvector? (make-fxvector 5)))
+    
+    (immutable-fxvector? (fxvector->immutable-fxvector (fxvector)))
+    (not (mutable-fxvector? (fxvector->immutable-fxvector (fxvector))))
+    (not (immutable-fxvector? (fxvector)))
+    (mutable-fxvector? (fxvector))
+    
+    (not (immutable-fxvector? (fxvector-copy immutable-123-fxvector)))
+
+    (error? (fxvector-set! immutable-123-fxvector 0 1))
+    (error? (fxvector-fill! immutable-123-fxvector 0))
+)
diff --git a/mats/bytevector.ms b/mats/bytevector.ms
index 3252188d01..44ffb9c556 100644
--- a/mats/bytevector.ms
+++ b/mats/bytevector.ms
@@ -10923,3 +10923,91 @@
                         ($bytevector-xor bv1 bv1))
           (errorf #f "bytevector-xor failed on ~s and ~s" bv1 bv1)))))
 )
+
+(mat bytevector->immutable-bytevector
+    (begin
+      (define immutable-100-bytevector
+        (bytevector->immutable-bytevector (make-bytevector 100 42)))
+      #t)
+    
+    (immutable-bytevector? immutable-100-bytevector)
+    (not (mutable-bytevector? immutable-100-bytevector))
+    
+    (equal? (make-bytevector 100 42) immutable-100-bytevector)
+    (eq? immutable-100-bytevector
+         (bytevector->immutable-bytevector immutable-100-bytevector))
+    
+    (not (immutable-bytevector? (make-bytevector 5)))
+    (mutable-bytevector? (make-bytevector 5))
+    
+    (immutable-bytevector? (bytevector->immutable-bytevector (bytevector)))
+    (not (mutable-bytevector? (bytevector->immutable-bytevector (bytevector))))
+    (not (immutable-bytevector? (bytevector)))
+    (mutable-bytevector? (bytevector))
+    
+    (not (immutable-bytevector? (bytevector-copy immutable-100-bytevector)))
+
+    ;; Make sure `...set!` functions check for mutability:
+    (error? (bytevector-uint-set! immutable-100-bytevector 0 1 (endianness big) 4))
+    (error? (bytevector-sint-set! immutable-100-bytevector 0 1 (endianness big) 4))
+    (error? (bytevector-u8-set! immutable-100-bytevector 0 1))
+    (error? (bytevector-s8-set! immutable-100-bytevector 0 1))
+    (error? (bytevector-u16-set! immutable-100-bytevector 0 1 (endianness big)))
+    (error? (bytevector-s16-set! immutable-100-bytevector 0 1 (endianness big)))
+    (error? (bytevector-u16-native-set! immutable-100-bytevector 0 1))
+    (error? (bytevector-s16-native-set! immutable-100-bytevector 0 1))
+    (error? (bytevector-u24-set! immutable-100-bytevector 0 1 (endianness big)))
+    (error? (bytevector-s24-set! immutable-100-bytevector 0 1 (endianness big)))
+    (error? (bytevector-u32-set! immutable-100-bytevector 0 1 (endianness big)))
+    (error? (bytevector-s32-set! immutable-100-bytevector 0 1 (endianness big)))
+    (error? (bytevector-u32-native-set! immutable-100-bytevector 0 1))
+    (error? (bytevector-s32-native-set! immutable-100-bytevector 0 1))
+    (error? (bytevector-u40-set! immutable-100-bytevector 0 1 (endianness big)))
+    (error? (bytevector-s40-set! immutable-100-bytevector 0 1 (endianness big)))
+    (error? (bytevector-u48-set! immutable-100-bytevector 0 1 (endianness big)))
+    (error? (bytevector-s48-set! immutable-100-bytevector 0 1 (endianness big)))
+    (error? (bytevector-u56-set! immutable-100-bytevector 0 1 (endianness big)))
+    (error? (bytevector-s56-set! immutable-100-bytevector 0 1 (endianness big)))
+    (error? (bytevector-u64-set! immutable-100-bytevector 0 1 (endianness big)))
+    (error? (bytevector-s64-set! immutable-100-bytevector 0 1 (endianness big)))
+    (error? (bytevector-u64-native-set! immutable-100-bytevector 0 1))
+    (error? (bytevector-s64-native-set! immutable-100-bytevector 0 1))
+    (error? (bytevector-ieee-single-set! immutable-100-bytevector 0 1.0 (endianness big)))
+    (error? (bytevector-ieee-double-set! immutable-100-bytevector 0 1.0 (endianness big)))
+    (error? (bytevector-ieee-single-native-set! immutable-100-bytevector 0 1.0))
+    (error? (bytevector-ieee-double-native-set! immutable-100-bytevector 0 1.0))
+    
+    (error? (bytevector-fill! immutable-100-bytevector 0))
+    (error? (bytevector-copy! '#vu8(4 5 6) 0 immutable-100-bytevector 0 3))
+    (error? (bytevector-truncate! immutable-100-bytevector 1))
+
+    ;; Make sure `...ref!` functions *don't* accidentally check for mutability:
+    (number? (bytevector-uint-ref immutable-100-bytevector 0 (endianness big) 4))
+    (number? (bytevector-sint-ref immutable-100-bytevector 0 (endianness big) 4))
+    (number? (bytevector-u8-ref immutable-100-bytevector 0))
+    (number? (bytevector-s8-ref immutable-100-bytevector 0))
+    (number? (bytevector-u16-ref immutable-100-bytevector 0 (endianness big)))
+    (number? (bytevector-s16-ref immutable-100-bytevector 0 (endianness big)))
+    (number? (bytevector-u16-native-ref immutable-100-bytevector 0))
+    (number? (bytevector-s16-native-ref immutable-100-bytevector 0))
+    (number? (bytevector-u24-ref immutable-100-bytevector 0 (endianness big)))
+    (number? (bytevector-s24-ref immutable-100-bytevector 0 (endianness big)))
+    (number? (bytevector-u32-ref immutable-100-bytevector 0 (endianness big)))
+    (number? (bytevector-s32-ref immutable-100-bytevector 0 (endianness big)))
+    (number? (bytevector-u32-native-ref immutable-100-bytevector 0))
+    (number? (bytevector-s32-native-ref immutable-100-bytevector 0))
+    (number? (bytevector-u40-ref immutable-100-bytevector 0 (endianness big)))
+    (number? (bytevector-s40-ref immutable-100-bytevector 0 (endianness big)))
+    (number? (bytevector-u48-ref immutable-100-bytevector 0 (endianness big)))
+    (number? (bytevector-s48-ref immutable-100-bytevector 0 (endianness big)))
+    (number? (bytevector-u56-ref immutable-100-bytevector 0 (endianness big)))
+    (number? (bytevector-s56-ref immutable-100-bytevector 0 (endianness big)))
+    (number? (bytevector-u64-ref immutable-100-bytevector 0 (endianness big)))
+    (number? (bytevector-s64-ref immutable-100-bytevector 0 (endianness big)))
+    (number? (bytevector-u64-native-ref immutable-100-bytevector 0))
+    (number? (bytevector-s64-native-ref immutable-100-bytevector 0))
+    (number? (bytevector-ieee-single-ref immutable-100-bytevector 0 (endianness big)))
+    (number? (bytevector-ieee-double-ref immutable-100-bytevector 0 (endianness big)))
+    (number? (bytevector-ieee-single-native-ref immutable-100-bytevector 0))
+    (number? (bytevector-ieee-double-native-ref immutable-100-bytevector 0))
+)
diff --git a/mats/misc.ms b/mats/misc.ms
index 25fb70c79d..e8083d5fcd 100644
--- a/mats/misc.ms
+++ b/mats/misc.ms
@@ -4927,3 +4927,41 @@
   (error? ; invalid argument
     (procedure-arity-mask 17))
   )
+
+(mat fasl-immutable
+  (begin
+    (define immutable-objs (list (vector->immutable-vector '#(1 2 3))
+                                 (fxvector->immutable-fxvector '#vfx(1 2 3))
+                                 (string->immutable-string "abc")
+                                 (bytevector->immutable-bytevector #vu8(1 2 3))
+                                 (box-immutable 1)))
+    (define immutable-zero-objs (list (vector->immutable-vector '#())
+                                      (fxvector->immutable-fxvector '#vfx())
+                                      (string->immutable-string "")
+                                      (bytevector->immutable-bytevector #vu8())
+                                      (box-immutable 1)))
+    (define (immutable? l)
+      (and (immutable-vector? (list-ref l 0))
+           (immutable-fxvector? (list-ref l 1))
+           (immutable-string? (list-ref l 2))
+           (immutable-bytevector? (list-ref l 3))
+           (immutable-box? (list-ref l 4))))
+    (define (round-trip l)
+      (let-values ([(o get) (open-bytevector-output-port)])
+        (fasl-write l o)
+        (immutable? (fasl-read (open-bytevector-input-port (get))))))
+    #t)
+
+  (immutable? immutable-objs)
+  (immutable? immutable-zero-objs)
+  (round-trip immutable-objs)
+  (round-trip immutable-zero-objs)
+
+  ;; Make sure `fasl-read` didn't mark "mutable" null values
+  ;; as immutable:
+  (mutable-vector? '#())
+  (mutable-fxvector? '#vfx())
+  (mutable-string? "")
+  (mutable-bytevector? '#vu8())
+  
+ )
diff --git a/mats/patch-compile-0-f-t-f b/mats/patch-compile-0-f-t-f
index 4f6a0d0abf..9bfceb4b64 100644
--- a/mats/patch-compile-0-f-t-f
+++ b/mats/patch-compile-0-f-t-f
@@ -1,5 +1,5 @@
-*** errors-compile-0-f-f-f	2016-05-01 13:38:30.812572752 -0400
---- errors-compile-0-f-t-f	2016-05-01 13:17:27.556633016 -0400
+*** errors-compile-0-f-f-f	2017-03-15 00:21:57.000000000 -0400
+--- errors-compile-0-f-t-f	2017-03-14 23:53:20.000000000 -0400
 ***************
 *** 125,131 ****
   3.mo:Expected error in mat dipa-letrec: "attempt to reference undefined variable a".
@@ -58,7 +58,7 @@
   3.mo:Expected error in mat mrvs: "attempt to apply non-procedure 17".
   3.mo:Expected error in mat mrvs: "returned two values to single value return context".
 ***************
-*** 3607,3613 ****
+*** 3645,3651 ****
   misc.mo:Expected error in mat cpletrec: "foreign-procedure: no entry for "foo"".
   misc.mo:Expected error in mat cpletrec: "attempt to reference undefined variable q".
   misc.mo:Expected error in mat cpletrec: "attempt to reference undefined variable bar".
@@ -66,7 +66,7 @@
   misc.mo:Expected error in mat cpletrec: "attempt to reference undefined variable b".
   misc.mo:Expected error in mat cpletrec: "attempt to reference undefined variable b".
   misc.mo:Expected error in mat cpletrec: "attempt to reference undefined variable a".
---- 3607,3613 ----
+--- 3645,3651 ----
   misc.mo:Expected error in mat cpletrec: "foreign-procedure: no entry for "foo"".
   misc.mo:Expected error in mat cpletrec: "attempt to reference undefined variable q".
   misc.mo:Expected error in mat cpletrec: "attempt to reference undefined variable bar".
@@ -75,7 +75,7 @@
   misc.mo:Expected error in mat cpletrec: "attempt to reference undefined variable b".
   misc.mo:Expected error in mat cpletrec: "attempt to reference undefined variable a".
 ***************
-*** 7050,7057 ****
+*** 7095,7102 ****
   7.mo:Expected error in mat bytes-allocated: "bytes-allocated: invalid space gnu".
   7.mo:Expected error in mat error: "a: hit me!".
   7.mo:Expected error in mat error: "f: n is 0".
@@ -84,7 +84,7 @@
   record.mo:Expected error in mat record2: "invalid value 3 for foreign type double-float".
   record.mo:Expected error in mat record2: "3 is not of type #<record type fudge>".
   record.mo:Expected error in mat record2: "make-record-type: invalid field list ((immutable double-float a) . b)".
---- 7050,7057 ----
+--- 7095,7102 ----
   7.mo:Expected error in mat bytes-allocated: "bytes-allocated: invalid space gnu".
   7.mo:Expected error in mat error: "a: hit me!".
   7.mo:Expected error in mat error: "f: n is 0".
@@ -94,7 +94,7 @@
   record.mo:Expected error in mat record2: "3 is not of type #<record type fudge>".
   record.mo:Expected error in mat record2: "make-record-type: invalid field list ((immutable double-float a) . b)".
 ***************
-*** 7059,7073 ****
+*** 7104,7118 ****
   record.mo:Expected error in mat type-descriptor: "invalid syntax (type-descriptor 3)".
   record.mo:Expected error in mat type-descriptor: "type-descriptor: unrecognized record car".
   record.mo:Expected error in mat record3: "variable set-fudge-a! is not bound".
@@ -110,7 +110,7 @@
   record.mo:Expected error in mat record9: "record-reader: invalid input #f".
   record.mo:Expected error in mat record9: "record-reader: invalid second argument fudge".
   record.mo:Expected error in mat record9: "record-reader: invalid second argument fudge".
---- 7059,7073 ----
+--- 7104,7118 ----
   record.mo:Expected error in mat type-descriptor: "invalid syntax (type-descriptor 3)".
   record.mo:Expected error in mat type-descriptor: "type-descriptor: unrecognized record car".
   record.mo:Expected error in mat record3: "variable set-fudge-a! is not bound".
@@ -127,7 +127,7 @@
   record.mo:Expected error in mat record9: "record-reader: invalid second argument fudge".
   record.mo:Expected error in mat record9: "record-reader: invalid second argument fudge".
 ***************
-*** 7080,7105 ****
+*** 7125,7150 ****
   record.mo:Expected error in mat record10: "read: unresolvable cycle constructing record of type #<record type bar> at char 3 of #<input port string>".
   record.mo:Expected error in mat record16: "read: unresolvable cycle constructing record of type #<record type bazar> at char 3 of #<input port string>".
   record.mo:Expected error in mat record16: "read: unresolvable cycle constructing record of type #<record type bazar> at char 3 of #<input port string>".
@@ -154,7 +154,7 @@
   record.mo:Expected error in mat foreign-data: "foreign-alloc: 0 is not a positive fixnum".
   record.mo:Expected error in mat foreign-data: "foreign-alloc: <int> is not a positive fixnum".
   record.mo:Expected error in mat foreign-data: "foreign-alloc: -5 is not a positive fixnum".
---- 7080,7105 ----
+--- 7125,7150 ----
   record.mo:Expected error in mat record10: "read: unresolvable cycle constructing record of type #<record type bar> at char 3 of #<input port string>".
   record.mo:Expected error in mat record16: "read: unresolvable cycle constructing record of type #<record type bazar> at char 3 of #<input port string>".
   record.mo:Expected error in mat record16: "read: unresolvable cycle constructing record of type #<record type bazar> at char 3 of #<input port string>".
@@ -182,7 +182,7 @@
   record.mo:Expected error in mat foreign-data: "foreign-alloc: <int> is not a positive fixnum".
   record.mo:Expected error in mat foreign-data: "foreign-alloc: -5 is not a positive fixnum".
 ***************
-*** 7221,7259 ****
+*** 7266,7304 ****
   record.mo:Expected error in mat record22: "invalid field specifier (immutable creepy q)".
   record.mo:Expected error in mat record22: "invalid field specifier (immutable creepy q)".
   record.mo:Expected error in mat record23: "make-record-type: cannot extend sealed record type #<record type foo>".
@@ -222,7 +222,7 @@
   record.mo:Expected error in mat record?: "record?: 4 is not a record type descriptor".
   record.mo:Expected error in mat record?: "record?: a is not a record type descriptor".
   record.mo:Expected error in mat record?: "record?: #(1) is not a record type descriptor".
---- 7221,7259 ----
+--- 7266,7304 ----
   record.mo:Expected error in mat record22: "invalid field specifier (immutable creepy q)".
   record.mo:Expected error in mat record22: "invalid field specifier (immutable creepy q)".
   record.mo:Expected error in mat record23: "make-record-type: cannot extend sealed record type #<record type foo>".
@@ -263,7 +263,7 @@
   record.mo:Expected error in mat record?: "record?: a is not a record type descriptor".
   record.mo:Expected error in mat record?: "record?: #(1) is not a record type descriptor".
 ***************
-*** 7268,7324 ****
+*** 7313,7369 ****
   record.mo:Expected error in mat r6rs-records-procedural: "make-record-constructor-descriptor: invalid protocol flimflam".
   record.mo:Expected error in mat r6rs-records-procedural: "attempt to apply non-procedure not-a-procedure".
   record.mo:Expected error in mat r6rs-records-procedural: "attempt to apply non-procedure spam".
@@ -321,7 +321,7 @@
   record.mo:Expected error in mat r6rs-records-syntactic: "define-record-type: incompatible record type cpoint - different parent".
   record.mo:Expected error in mat r6rs-records-syntactic: "define-record-type: incompatible record type cpoint - different parent".
   record.mo:Expected error in mat r6rs-records-syntactic: "cannot extend define-record-type parent fratrat".
---- 7268,7324 ----
+--- 7313,7369 ----
   record.mo:Expected error in mat r6rs-records-procedural: "make-record-constructor-descriptor: invalid protocol flimflam".
   record.mo:Expected error in mat r6rs-records-procedural: "attempt to apply non-procedure not-a-procedure".
   record.mo:Expected error in mat r6rs-records-procedural: "attempt to apply non-procedure spam".
diff --git a/mats/patch-compile-0-t-f-f b/mats/patch-compile-0-t-f-f
index 9ca196d46b..426a07dd60 100644
--- a/mats/patch-compile-0-t-f-f
+++ b/mats/patch-compile-0-t-f-f
@@ -1,5 +1,5 @@
-*** errors-compile-0-f-f-f	2016-05-01 13:38:30.812572752 -0400
---- errors-compile-0-t-f-f	2016-05-01 13:22:13.215255991 -0400
+*** errors-compile-0-f-f-f	2017-03-15 00:21:57.000000000 -0400
+--- errors-compile-0-t-f-f	2017-03-14 23:59:50.000000000 -0400
 ***************
 *** 93,99 ****
   3.mo:Expected error in mat case-lambda: "incorrect number of arguments to #<procedure foo>".
@@ -64,7 +64,7 @@
   4.mo:Expected error in mat apply: "apply: 4 is not a proper list".
   4.mo:Expected error in mat apply: "apply: (3 4 5 6 7 8 . 9) is not a proper list".
 ***************
-*** 491,498 ****
+*** 493,500 ****
   4.mo:Expected error in mat $primitive: "invalid primitive name fubar".
   4.mo:Expected error in mat $primitive: "incorrect argument count in call (car (quote a) (quote b))".
   4.mo:Expected error in mat $primitive: "car: 3 is not a pair".
@@ -73,7 +73,7 @@
   5_1.mo:Expected error in mat boolean=?: "boolean=?: 3 is not a boolean".
   5_1.mo:Expected error in mat boolean=?: "boolean=?: 3 is not a boolean".
   5_1.mo:Expected error in mat boolean=?: "boolean=?: 3 is not a boolean".
---- 491,498 ----
+--- 493,500 ----
   4.mo:Expected error in mat $primitive: "invalid primitive name fubar".
   4.mo:Expected error in mat $primitive: "incorrect argument count in call (car (quote a) (quote b))".
   4.mo:Expected error in mat $primitive: "car: 3 is not a pair".
@@ -83,7 +83,7 @@
   5_1.mo:Expected error in mat boolean=?: "boolean=?: 3 is not a boolean".
   5_1.mo:Expected error in mat boolean=?: "boolean=?: 3 is not a boolean".
 ***************
-*** 502,509 ****
+*** 504,511 ****
   5_1.mo:Expected error in mat boolean=?: "boolean=?: 3 is not a boolean".
   5_1.mo:Expected error in mat boolean=?: "boolean=?: 3 is not a boolean".
   5_1.mo:Expected error in mat boolean=?: "boolean=?: 3 is not a boolean".
@@ -92,7 +92,7 @@
   5_1.mo:Expected error in mat symbol=?: "symbol=?: 3 is not a symbol".
   5_1.mo:Expected error in mat symbol=?: "symbol=?: 3 is not a symbol".
   5_1.mo:Expected error in mat symbol=?: "symbol=?: 3 is not a symbol".
---- 502,509 ----
+--- 504,511 ----
   5_1.mo:Expected error in mat boolean=?: "boolean=?: 3 is not a boolean".
   5_1.mo:Expected error in mat boolean=?: "boolean=?: 3 is not a boolean".
   5_1.mo:Expected error in mat boolean=?: "boolean=?: 3 is not a boolean".
@@ -102,7 +102,7 @@
   5_1.mo:Expected error in mat symbol=?: "symbol=?: 3 is not a symbol".
   5_1.mo:Expected error in mat symbol=?: "symbol=?: 3 is not a symbol".
 ***************
-*** 545,552 ****
+*** 547,554 ****
   5_2.mo:Expected error in mat c....r-errors: "cddadr: incorrect list structure (a . b)".
   5_2.mo:Expected error in mat c....r-errors: "cdddar: incorrect list structure (a . b)".
   5_2.mo:Expected error in mat c....r-errors: "cddddr: incorrect list structure (a . b)".
@@ -111,7 +111,7 @@
   5_2.mo:Expected error in mat list-ref: "list-ref: a is not a proper list".
   5_2.mo:Expected error in mat list-ref: "list-ref: (a b . c) is not a proper list".
   5_2.mo:Expected error in mat list-ref: "list-ref: index 4 is out of range for list (a b)".
---- 545,552 ----
+--- 547,554 ----
   5_2.mo:Expected error in mat c....r-errors: "cddadr: incorrect list structure (a . b)".
   5_2.mo:Expected error in mat c....r-errors: "cdddar: incorrect list structure (a . b)".
   5_2.mo:Expected error in mat c....r-errors: "cddddr: incorrect list structure (a . b)".
@@ -121,7 +121,7 @@
   5_2.mo:Expected error in mat list-ref: "list-ref: (a b . c) is not a proper list".
   5_2.mo:Expected error in mat list-ref: "list-ref: index 4 is out of range for list (a b)".
 ***************
-*** 633,645 ****
+*** 635,647 ****
   5_2.mo:Expected error in mat append!: "append!: (b a b a b a ...) is circular".
   5_2.mo:Expected error in mat append!: "append!: (c d a b a b ...) is circular".
   5_2.mo:Expected error in mat append!: "append!: (a b . c) is not a proper list".
@@ -135,7 +135,7 @@
   5_2.mo:Expected error in mat reverse!: "reverse!: a is not a proper list".
   5_2.mo:Expected error in mat reverse!: "reverse!: (a b . c) is not a proper list".
   5_2.mo:Expected error in mat reverse!: "reverse!: (a b a b a b ...) is circular".
---- 633,645 ----
+--- 635,647 ----
   5_2.mo:Expected error in mat append!: "append!: (b a b a b a ...) is circular".
   5_2.mo:Expected error in mat append!: "append!: (c d a b a b ...) is circular".
   5_2.mo:Expected error in mat append!: "append!: (a b . c) is not a proper list".
@@ -150,7 +150,7 @@
   5_2.mo:Expected error in mat reverse!: "reverse!: (a b . c) is not a proper list".
   5_2.mo:Expected error in mat reverse!: "reverse!: (a b a b a b ...) is circular".
 ***************
-*** 652,669 ****
+*** 654,671 ****
   5_2.mo:Expected error in mat find: "find: improper list (a b . c)".
   5_2.mo:Expected error in mat find: "find: improper list (a b c . d)".
   5_2.mo:Expected error in mat find: "find: a is not a procedure".
@@ -169,7 +169,7 @@
   5_2.mo:Expected error in mat member: "member: improper list a".
   5_2.mo:Expected error in mat member: "member: cyclic list (a b a b a b ...)".
   5_2.mo:Expected error in mat member: "member: improper list (a b . c)".
---- 652,669 ----
+--- 654,671 ----
   5_2.mo:Expected error in mat find: "find: improper list (a b . c)".
   5_2.mo:Expected error in mat find: "find: improper list (a b c . d)".
   5_2.mo:Expected error in mat find: "find: a is not a procedure".
@@ -189,7 +189,7 @@
   5_2.mo:Expected error in mat member: "member: cyclic list (a b a b a b ...)".
   5_2.mo:Expected error in mat member: "member: improper list (a b . c)".
 ***************
-*** 706,715 ****
+*** 708,717 ****
   5_2.mo:Expected error in mat assv: "assv: cyclic alist ((a . 1) (b . 2) (3.2 . 3) ("a" . 4) (a . 1) (b . 2) ...)".
   5_2.mo:Expected error in mat assoc: "assoc: cyclic alist ((a . 1) (b . 2) (3.2 . 3) ("a" . 4) (a . 1) (b . 2) ...)".
   5_2.mo:Expected error in mat assoc: "assoc: cyclic alist ((a . 1) (b . 2) (3.2 . 3) ("a" . 4) (a . 1) (b . 2) ...)".
@@ -200,7 +200,7 @@
   5_2.mo:Expected error in mat sort: "sort: 3 is not a proper list".
   5_2.mo:Expected error in mat sort: "sort: #(1 2 3) is not a proper list".
   5_2.mo:Expected error in mat sort: "sort: (1 2 . 3) is not a proper list".
---- 706,715 ----
+--- 708,717 ----
   5_2.mo:Expected error in mat assv: "assv: cyclic alist ((a . 1) (b . 2) (3.2 . 3) ("a" . 4) (a . 1) (b . 2) ...)".
   5_2.mo:Expected error in mat assoc: "assoc: cyclic alist ((a . 1) (b . 2) (3.2 . 3) ("a" . 4) (a . 1) (b . 2) ...)".
   5_2.mo:Expected error in mat assoc: "assoc: cyclic alist ((a . 1) (b . 2) (3.2 . 3) ("a" . 4) (a . 1) (b . 2) ...)".
@@ -212,7 +212,7 @@
   5_2.mo:Expected error in mat sort: "sort: #(1 2 3) is not a proper list".
   5_2.mo:Expected error in mat sort: "sort: (1 2 . 3) is not a proper list".
 ***************
-*** 718,727 ****
+*** 720,729 ****
   5_2.mo:Expected error in mat sort: "sort: (q p a b a b ...) is circular".
   5_2.mo:Expected error in mat sort: "sort: (a b c) is not a procedure".
   5_2.mo:Expected error in mat sort: ">: b is not a real number".
@@ -223,7 +223,7 @@
   5_2.mo:Expected error in mat list-sort: "list-sort: 3 is not a proper list".
   5_2.mo:Expected error in mat list-sort: "list-sort: #(1 2 3) is not a proper list".
   5_2.mo:Expected error in mat list-sort: "list-sort: (1 2 . 3) is not a proper list".
---- 718,727 ----
+--- 720,729 ----
   5_2.mo:Expected error in mat sort: "sort: (q p a b a b ...) is circular".
   5_2.mo:Expected error in mat sort: "sort: (a b c) is not a procedure".
   5_2.mo:Expected error in mat sort: ">: b is not a real number".
@@ -235,7 +235,7 @@
   5_2.mo:Expected error in mat list-sort: "list-sort: #(1 2 3) is not a proper list".
   5_2.mo:Expected error in mat list-sort: "list-sort: (1 2 . 3) is not a proper list".
 ***************
-*** 730,739 ****
+*** 732,741 ****
   5_2.mo:Expected error in mat list-sort: "list-sort: (q p a b a b ...) is circular".
   5_2.mo:Expected error in mat list-sort: "list-sort: (a b c) is not a procedure".
   5_2.mo:Expected error in mat list-sort: ">: b is not a real number".
@@ -246,7 +246,7 @@
   5_2.mo:Expected error in mat sort!: "sort!: 3 is not a proper list".
   5_2.mo:Expected error in mat sort!: "sort!: #(1 2 3) is not a proper list".
   5_2.mo:Expected error in mat sort!: "sort!: (1 2 . 3) is not a proper list".
---- 730,739 ----
+--- 732,741 ----
   5_2.mo:Expected error in mat list-sort: "list-sort: (q p a b a b ...) is circular".
   5_2.mo:Expected error in mat list-sort: "list-sort: (a b c) is not a procedure".
   5_2.mo:Expected error in mat list-sort: ">: b is not a real number".
@@ -258,7 +258,7 @@
   5_2.mo:Expected error in mat sort!: "sort!: #(1 2 3) is not a proper list".
   5_2.mo:Expected error in mat sort!: "sort!: (1 2 . 3) is not a proper list".
 ***************
-*** 762,779 ****
+*** 764,781 ****
   5_2.mo:Expected error in mat iota: "iota: -1 is not a nonnegative fixnum".
   5_2.mo:Expected error in mat iota: "iota: 1000000000000000000000000000000 is not a nonnegative fixnum".
   5_2.mo:Expected error in mat iota: "iota: 3/4 is not a nonnegative fixnum".
@@ -277,7 +277,7 @@
   5_3.mo:Expected error in mat r6rs:string->number: "string->number: a is not a string".
   5_3.mo:Expected error in mat r6rs:string->number: "string->number: 0 is not a valid radix".
   5_3.mo:Expected error in mat r6rs:string->number: "string->number: 37 is not a valid radix".
---- 762,779 ----
+--- 764,781 ----
   5_2.mo:Expected error in mat iota: "iota: -1 is not a nonnegative fixnum".
   5_2.mo:Expected error in mat iota: "iota: 1000000000000000000000000000000 is not a nonnegative fixnum".
   5_2.mo:Expected error in mat iota: "iota: 3/4 is not a nonnegative fixnum".
@@ -297,7 +297,7 @@
   5_3.mo:Expected error in mat r6rs:string->number: "string->number: 0 is not a valid radix".
   5_3.mo:Expected error in mat r6rs:string->number: "string->number: 37 is not a valid radix".
 ***************
-*** 784,790 ****
+*** 786,792 ****
   5_3.mo:Expected error in mat r6rs:string->number: "string->number: <int> is not a valid radix".
   5_3.mo:Expected error in mat r6rs:string->number: "string->number: 36 is not a valid radix".
   5_3.mo:Expected error in mat r6rs:string->number: "string->number: a is not a valid radix".
@@ -305,7 +305,7 @@
   5_3.mo:Expected error in mat number->string: "number->string: a is not a number".
   5_3.mo:Expected error in mat number->string: "number->string: a is not a number".
   5_3.mo:Expected error in mat number->string: "number->string: a is not a number".
---- 784,790 ----
+--- 786,792 ----
   5_3.mo:Expected error in mat r6rs:string->number: "string->number: <int> is not a valid radix".
   5_3.mo:Expected error in mat r6rs:string->number: "string->number: 36 is not a valid radix".
   5_3.mo:Expected error in mat r6rs:string->number: "string->number: a is not a valid radix".
@@ -314,7 +314,7 @@
   5_3.mo:Expected error in mat number->string: "number->string: a is not a number".
   5_3.mo:Expected error in mat number->string: "number->string: a is not a number".
 ***************
-*** 820,826 ****
+*** 822,828 ****
   5_3.mo:Expected error in mat r6rs:number->string: "number->string: a precision is specified and radix 16 is not 10".
   5_3.mo:Expected error in mat exact?: "exact?: a is not a number".
   5_3.mo:Expected error in mat inexact?: "inexact?: () is not a number".
@@ -322,7 +322,7 @@
   5_3.mo:Expected error in mat =: "=: a is not a number".
   5_3.mo:Expected error in mat =: "=: a is not a number".
   5_3.mo:Expected error in mat =: "=: a is not a number".
---- 820,826 ----
+--- 822,828 ----
   5_3.mo:Expected error in mat r6rs:number->string: "number->string: a precision is specified and radix 16 is not 10".
   5_3.mo:Expected error in mat exact?: "exact?: a is not a number".
   5_3.mo:Expected error in mat inexact?: "inexact?: () is not a number".
@@ -331,7 +331,7 @@
   5_3.mo:Expected error in mat =: "=: a is not a number".
   5_3.mo:Expected error in mat =: "=: a is not a number".
 ***************
-*** 829,835 ****
+*** 831,837 ****
   5_3.mo:Expected error in mat =: "=: a is not a number".
   5_3.mo:Expected error in mat =: "=: a is not a number".
   5_3.mo:Expected error in mat =: "=: a is not a number".
@@ -339,7 +339,7 @@
   5_3.mo:Expected error in mat <: "<: a is not a real number".
   5_3.mo:Expected error in mat <: "<: a is not a real number".
   5_3.mo:Expected error in mat <: "<: a is not a real number".
---- 829,835 ----
+--- 831,837 ----
   5_3.mo:Expected error in mat =: "=: a is not a number".
   5_3.mo:Expected error in mat =: "=: a is not a number".
   5_3.mo:Expected error in mat =: "=: a is not a number".
@@ -348,7 +348,7 @@
   5_3.mo:Expected error in mat <: "<: a is not a real number".
   5_3.mo:Expected error in mat <: "<: a is not a real number".
 ***************
-*** 849,855 ****
+*** 851,857 ****
   5_3.mo:Expected error in mat <: "<: 2.0+1.0i is not a real number".
   5_3.mo:Expected error in mat <: "<: 2+1i is not a real number".
   5_3.mo:Expected error in mat <: "<: 3+1i is not a real number".
@@ -356,7 +356,7 @@
   5_3.mo:Expected error in mat <=: "<=: a is not a real number".
   5_3.mo:Expected error in mat <=: "<=: a is not a real number".
   5_3.mo:Expected error in mat <=: "<=: a is not a real number".
---- 849,855 ----
+--- 851,857 ----
   5_3.mo:Expected error in mat <: "<: 2.0+1.0i is not a real number".
   5_3.mo:Expected error in mat <: "<: 2+1i is not a real number".
   5_3.mo:Expected error in mat <: "<: 3+1i is not a real number".
@@ -365,7 +365,7 @@
   5_3.mo:Expected error in mat <=: "<=: a is not a real number".
   5_3.mo:Expected error in mat <=: "<=: a is not a real number".
 ***************
-*** 869,875 ****
+*** 871,877 ****
   5_3.mo:Expected error in mat <=: "<=: 2.0+1.0i is not a real number".
   5_3.mo:Expected error in mat <=: "<=: 2+1i is not a real number".
   5_3.mo:Expected error in mat <=: "<=: 3+1i is not a real number".
@@ -373,7 +373,7 @@
   5_3.mo:Expected error in mat >: ">: a is not a real number".
   5_3.mo:Expected error in mat >: ">: a is not a real number".
   5_3.mo:Expected error in mat >: ">: a is not a real number".
---- 869,875 ----
+--- 871,877 ----
   5_3.mo:Expected error in mat <=: "<=: 2.0+1.0i is not a real number".
   5_3.mo:Expected error in mat <=: "<=: 2+1i is not a real number".
   5_3.mo:Expected error in mat <=: "<=: 3+1i is not a real number".
@@ -382,7 +382,7 @@
   5_3.mo:Expected error in mat >: ">: a is not a real number".
   5_3.mo:Expected error in mat >: ">: a is not a real number".
 ***************
-*** 889,895 ****
+*** 891,897 ****
   5_3.mo:Expected error in mat >: ">: 2.0+1.0i is not a real number".
   5_3.mo:Expected error in mat >: ">: 2+1i is not a real number".
   5_3.mo:Expected error in mat >: ">: 3+1i is not a real number".
@@ -390,7 +390,7 @@
   5_3.mo:Expected error in mat >=: ">=: a is not a real number".
   5_3.mo:Expected error in mat >=: ">=: a is not a real number".
   5_3.mo:Expected error in mat >=: ">=: a is not a real number".
---- 889,895 ----
+--- 891,897 ----
   5_3.mo:Expected error in mat >: ">: 2.0+1.0i is not a real number".
   5_3.mo:Expected error in mat >: ">: 2+1i is not a real number".
   5_3.mo:Expected error in mat >: ">: 3+1i is not a real number".
@@ -399,7 +399,7 @@
   5_3.mo:Expected error in mat >=: ">=: a is not a real number".
   5_3.mo:Expected error in mat >=: ">=: a is not a real number".
 ***************
-*** 909,916 ****
+*** 911,918 ****
   5_3.mo:Expected error in mat >=: ">=: 2.0+1.0i is not a real number".
   5_3.mo:Expected error in mat >=: ">=: 2+1i is not a real number".
   5_3.mo:Expected error in mat >=: ">=: 3+1i is not a real number".
@@ -408,7 +408,7 @@
   5_3.mo:Expected error in mat r6rs:=: "=: a is not a number".
   5_3.mo:Expected error in mat r6rs:=: "=: a is not a number".
   5_3.mo:Expected error in mat r6rs:=: "=: a is not a number".
---- 909,916 ----
+--- 911,918 ----
   5_3.mo:Expected error in mat >=: ">=: 2.0+1.0i is not a real number".
   5_3.mo:Expected error in mat >=: ">=: 2+1i is not a real number".
   5_3.mo:Expected error in mat >=: ">=: 3+1i is not a real number".
@@ -418,7 +418,7 @@
   5_3.mo:Expected error in mat r6rs:=: "=: a is not a number".
   5_3.mo:Expected error in mat r6rs:=: "=: a is not a number".
 ***************
-*** 918,925 ****
+*** 920,927 ****
   5_3.mo:Expected error in mat r6rs:=: "=: a is not a number".
   5_3.mo:Expected error in mat r6rs:=: "=: a is not a number".
   5_3.mo:Expected error in mat r6rs:=: "=: a is not a number".
@@ -427,7 +427,7 @@
   5_3.mo:Expected error in mat r6rs:<: "<: a is not a real number".
   5_3.mo:Expected error in mat r6rs:<: "<: a is not a real number".
   5_3.mo:Expected error in mat r6rs:<: "<: a is not a real number".
---- 918,925 ----
+--- 920,927 ----
   5_3.mo:Expected error in mat r6rs:=: "=: a is not a number".
   5_3.mo:Expected error in mat r6rs:=: "=: a is not a number".
   5_3.mo:Expected error in mat r6rs:=: "=: a is not a number".
@@ -437,7 +437,7 @@
   5_3.mo:Expected error in mat r6rs:<: "<: a is not a real number".
   5_3.mo:Expected error in mat r6rs:<: "<: a is not a real number".
 ***************
-*** 930,937 ****
+*** 932,939 ****
   5_3.mo:Expected error in mat r6rs:<: "<: 2.0+1.0i is not a real number".
   5_3.mo:Expected error in mat r6rs:<: "<: 2+1i is not a real number".
   5_3.mo:Expected error in mat r6rs:<: "<: 3+1i is not a real number".
@@ -446,7 +446,7 @@
   5_3.mo:Expected error in mat r6rs:<=: "<=: a is not a real number".
   5_3.mo:Expected error in mat r6rs:<=: "<=: a is not a real number".
   5_3.mo:Expected error in mat r6rs:<=: "<=: a is not a real number".
---- 930,937 ----
+--- 932,939 ----
   5_3.mo:Expected error in mat r6rs:<: "<: 2.0+1.0i is not a real number".
   5_3.mo:Expected error in mat r6rs:<: "<: 2+1i is not a real number".
   5_3.mo:Expected error in mat r6rs:<: "<: 3+1i is not a real number".
@@ -456,7 +456,7 @@
   5_3.mo:Expected error in mat r6rs:<=: "<=: a is not a real number".
   5_3.mo:Expected error in mat r6rs:<=: "<=: a is not a real number".
 ***************
-*** 942,949 ****
+*** 944,951 ****
   5_3.mo:Expected error in mat r6rs:<=: "<=: 2.0+1.0i is not a real number".
   5_3.mo:Expected error in mat r6rs:<=: "<=: 2+1i is not a real number".
   5_3.mo:Expected error in mat r6rs:<=: "<=: 3+1i is not a real number".
@@ -465,7 +465,7 @@
   5_3.mo:Expected error in mat r6rs:>: ">: a is not a real number".
   5_3.mo:Expected error in mat r6rs:>: ">: a is not a real number".
   5_3.mo:Expected error in mat r6rs:>: ">: a is not a real number".
---- 942,949 ----
+--- 944,951 ----
   5_3.mo:Expected error in mat r6rs:<=: "<=: 2.0+1.0i is not a real number".
   5_3.mo:Expected error in mat r6rs:<=: "<=: 2+1i is not a real number".
   5_3.mo:Expected error in mat r6rs:<=: "<=: 3+1i is not a real number".
@@ -475,7 +475,7 @@
   5_3.mo:Expected error in mat r6rs:>: ">: a is not a real number".
   5_3.mo:Expected error in mat r6rs:>: ">: a is not a real number".
 ***************
-*** 954,961 ****
+*** 956,963 ****
   5_3.mo:Expected error in mat r6rs:>: ">: 2.0+1.0i is not a real number".
   5_3.mo:Expected error in mat r6rs:>: ">: 2+1i is not a real number".
   5_3.mo:Expected error in mat r6rs:>: ">: 3+1i is not a real number".
@@ -484,7 +484,7 @@
   5_3.mo:Expected error in mat r6rs:>=: ">=: a is not a real number".
   5_3.mo:Expected error in mat r6rs:>=: ">=: a is not a real number".
   5_3.mo:Expected error in mat r6rs:>=: ">=: a is not a real number".
---- 954,961 ----
+--- 956,963 ----
   5_3.mo:Expected error in mat r6rs:>: ">: 2.0+1.0i is not a real number".
   5_3.mo:Expected error in mat r6rs:>: ">: 2+1i is not a real number".
   5_3.mo:Expected error in mat r6rs:>: ">: 3+1i is not a real number".
@@ -494,7 +494,7 @@
   5_3.mo:Expected error in mat r6rs:>=: ">=: a is not a real number".
   5_3.mo:Expected error in mat r6rs:>=: ">=: a is not a real number".
 ***************
-*** 975,981 ****
+*** 977,983 ****
   5_3.mo:Expected error in mat +: "oops".
   5_3.mo:Expected error in mat +: "+: #f is not a number".
   5_3.mo:Expected error in mat +: "+: #f is not a number".
@@ -502,7 +502,7 @@
   5_3.mo:Expected error in mat -: "-: a is not a number".
   5_3.mo:Expected error in mat -: "-: a is not a number".
   5_3.mo:Expected error in mat -: "-: a is not a number".
---- 975,981 ----
+--- 977,983 ----
   5_3.mo:Expected error in mat +: "oops".
   5_3.mo:Expected error in mat +: "+: #f is not a number".
   5_3.mo:Expected error in mat +: "+: #f is not a number".
@@ -511,7 +511,7 @@
   5_3.mo:Expected error in mat -: "-: a is not a number".
   5_3.mo:Expected error in mat -: "-: a is not a number".
 ***************
-*** 988,994 ****
+*** 990,996 ****
   5_3.mo:Expected error in mat *: "*: a is not a number".
   5_3.mo:Expected error in mat *: "*: #f is not a number".
   5_3.mo:Expected error in mat *: "*: #f is not a number".
@@ -519,7 +519,7 @@
   5_3.mo:Expected error in mat /: "/: a is not a number".
   5_3.mo:Expected error in mat /: "/: a is not a number".
   5_3.mo:Expected error in mat /: "/: a is not a number".
---- 988,994 ----
+--- 990,996 ----
   5_3.mo:Expected error in mat *: "*: a is not a number".
   5_3.mo:Expected error in mat *: "*: #f is not a number".
   5_3.mo:Expected error in mat *: "*: #f is not a number".
@@ -528,7 +528,7 @@
   5_3.mo:Expected error in mat /: "/: a is not a number".
   5_3.mo:Expected error in mat /: "/: a is not a number".
 ***************
-*** 1002,1065 ****
+*** 1004,1067 ****
   5_3.mo:Expected error in mat infinite?: "infinite?: a is not a real number".
   5_3.mo:Expected error in mat infinite?: "infinite?: 3+4i is not a real number".
   5_3.mo:Expected error in mat infinite?: "infinite?: 3.0-0.0i is not a real number".
@@ -593,7 +593,7 @@
   5_3.mo:Expected error in mat quotient: "quotient: a is not an integer".
   5_3.mo:Expected error in mat quotient: "quotient: a is not an integer".
   5_3.mo:Expected error in mat quotient: "quotient: 2/5 is not an integer".
---- 1002,1065 ----
+--- 1004,1067 ----
   5_3.mo:Expected error in mat infinite?: "infinite?: a is not a real number".
   5_3.mo:Expected error in mat infinite?: "infinite?: 3+4i is not a real number".
   5_3.mo:Expected error in mat infinite?: "infinite?: 3.0-0.0i is not a real number".
@@ -659,7 +659,7 @@
   5_3.mo:Expected error in mat quotient: "quotient: a is not an integer".
   5_3.mo:Expected error in mat quotient: "quotient: 2/5 is not an integer".
 ***************
-*** 1072,1081 ****
+*** 1074,1083 ****
   5_3.mo:Expected error in mat quotient: "quotient: 2+1i is not an integer".
   5_3.mo:Expected error in mat quotient: "quotient: 2+1i is not an integer".
   5_3.mo:Expected error in mat quotient: "quotient: 2.0+1.0i is not an integer".
@@ -670,7 +670,7 @@
   5_3.mo:Expected error in mat remainder: "remainder: a is not an integer".
   5_3.mo:Expected error in mat remainder: "remainder: a is not an integer".
   5_3.mo:Expected error in mat remainder: "remainder: 2/5 is not an integer".
---- 1072,1081 ----
+--- 1074,1083 ----
   5_3.mo:Expected error in mat quotient: "quotient: 2+1i is not an integer".
   5_3.mo:Expected error in mat quotient: "quotient: 2+1i is not an integer".
   5_3.mo:Expected error in mat quotient: "quotient: 2.0+1.0i is not an integer".
@@ -682,7 +682,7 @@
   5_3.mo:Expected error in mat remainder: "remainder: a is not an integer".
   5_3.mo:Expected error in mat remainder: "remainder: 2/5 is not an integer".
 ***************
-*** 1086,1094 ****
+*** 1088,1096 ****
   5_3.mo:Expected error in mat remainder: "remainder: 2.5 is not an integer".
   5_3.mo:Expected error in mat remainder: "remainder: 2.5 is not an integer".
   5_3.mo:Expected error in mat remainder: "remainder: -3+2i is not an integer".
@@ -692,7 +692,7 @@
   5_3.mo:Expected error in mat modulo: "modulo: a is not an integer".
   5_3.mo:Expected error in mat modulo: "modulo: a is not an integer".
   5_3.mo:Expected error in mat modulo: "modulo: 3/5 is not an integer".
---- 1086,1094 ----
+--- 1088,1096 ----
   5_3.mo:Expected error in mat remainder: "remainder: 2.5 is not an integer".
   5_3.mo:Expected error in mat remainder: "remainder: 2.5 is not an integer".
   5_3.mo:Expected error in mat remainder: "remainder: -3+2i is not an integer".
@@ -703,7 +703,7 @@
   5_3.mo:Expected error in mat modulo: "modulo: a is not an integer".
   5_3.mo:Expected error in mat modulo: "modulo: 3/5 is not an integer".
 ***************
-*** 1098,1143 ****
+*** 1100,1145 ****
   5_3.mo:Expected error in mat modulo: "modulo: 3.2 is not an integer".
   5_3.mo:Expected error in mat modulo: "modulo: -3.2 is not an integer".
   5_3.mo:Expected error in mat modulo: "modulo: -3+2i is not an integer".
@@ -750,7 +750,7 @@
   5_3.mo:Expected error in mat min: "min: a is not a real number".
   5_3.mo:Expected error in mat min: "min: a is not a real number".
   5_3.mo:Expected error in mat min: "min: a is not a real number".
---- 1098,1143 ----
+--- 1100,1145 ----
   5_3.mo:Expected error in mat modulo: "modulo: 3.2 is not an integer".
   5_3.mo:Expected error in mat modulo: "modulo: -3.2 is not an integer".
   5_3.mo:Expected error in mat modulo: "modulo: -3+2i is not an integer".
@@ -798,7 +798,7 @@
   5_3.mo:Expected error in mat min: "min: a is not a real number".
   5_3.mo:Expected error in mat min: "min: a is not a real number".
 ***************
-*** 1196,1218 ****
+*** 1198,1220 ****
   5_3.mo:Expected error in mat lcm: "lcm: +nan.0 is not an integer".
   5_3.mo:Expected error in mat lcm: "lcm: +nan.0 is not an integer".
   5_3.mo:Expected error in mat lcm: "lcm: +nan.0 is not an integer".
@@ -822,7 +822,7 @@
   5_3.mo:Expected error in mat random: "random: invalid argument a".
   5_3.mo:Expected error in mat random: "random: invalid argument -3".
   5_3.mo:Expected error in mat random: "random: invalid argument 0".
---- 1196,1218 ----
+--- 1198,1220 ----
   5_3.mo:Expected error in mat lcm: "lcm: +nan.0 is not an integer".
   5_3.mo:Expected error in mat lcm: "lcm: +nan.0 is not an integer".
   5_3.mo:Expected error in mat lcm: "lcm: +nan.0 is not an integer".
@@ -847,7 +847,7 @@
   5_3.mo:Expected error in mat random: "random: invalid argument -3".
   5_3.mo:Expected error in mat random: "random: invalid argument 0".
 ***************
-*** 1225,1263 ****
+*** 1227,1265 ****
   5_3.mo:Expected error in mat random-seed: "random-seed: invalid argument 0".
   5_3.mo:Expected error in mat random-seed: "random-seed: invalid argument -1".
   5_3.mo:Expected error in mat random-seed: "random-seed: invalid argument <int>".
@@ -887,7 +887,7 @@
   5_3.mo:Expected error in mat imag-part: "imag-part: a is not a complex number".
   5_3.mo:Expected error in mat make-rectangular: "make-rectangular: a is not a real number".
   5_3.mo:Expected error in mat make-rectangular: "make-rectangular: b is not a real number".
---- 1225,1263 ----
+--- 1227,1265 ----
   5_3.mo:Expected error in mat random-seed: "random-seed: invalid argument 0".
   5_3.mo:Expected error in mat random-seed: "random-seed: invalid argument -1".
   5_3.mo:Expected error in mat random-seed: "random-seed: invalid argument <int>".
@@ -928,7 +928,7 @@
   5_3.mo:Expected error in mat make-rectangular: "make-rectangular: a is not a real number".
   5_3.mo:Expected error in mat make-rectangular: "make-rectangular: b is not a real number".
 ***************
-*** 1267,1343 ****
+*** 1269,1345 ****
   5_3.mo:Expected error in mat make-polar: "make-polar: b is not a real number".
   5_3.mo:Expected error in mat make-polar: "make-polar: 3.4+0.0i is not a real number".
   5_3.mo:Expected error in mat make-polar: "make-polar: 3.4+0.0i is not a real number".
@@ -1006,7 +1006,7 @@
   5_3.mo:Expected error in mat bitwise-bit-field: "bitwise-bit-field: 35.0 is not an exact integer".
   5_3.mo:Expected error in mat bitwise-bit-field: "bitwise-bit-field: invalid start index 5.0".
   5_3.mo:Expected error in mat bitwise-bit-field: "bitwise-bit-field: invalid end index 8.0".
---- 1267,1343 ----
+--- 1269,1345 ----
   5_3.mo:Expected error in mat make-polar: "make-polar: b is not a real number".
   5_3.mo:Expected error in mat make-polar: "make-polar: 3.4+0.0i is not a real number".
   5_3.mo:Expected error in mat make-polar: "make-polar: 3.4+0.0i is not a real number".
@@ -1085,7 +1085,7 @@
   5_3.mo:Expected error in mat bitwise-bit-field: "bitwise-bit-field: invalid start index 5.0".
   5_3.mo:Expected error in mat bitwise-bit-field: "bitwise-bit-field: invalid end index 8.0".
 ***************
-*** 1348,1358 ****
+*** 1350,1360 ****
   5_3.mo:Expected error in mat bitwise-bit-field: "bitwise-bit-field: invalid end index -8".
   5_3.mo:Expected error in mat bitwise-bit-field: "bitwise-bit-field: invalid end index 3".
   5_3.mo:Expected error in mat bitwise-bit-field: "bitwise-bit-field: invalid end index <int>".
@@ -1097,7 +1097,7 @@
   5_3.mo:Expected error in mat bitwise-copy-bit-field: "bitwise-copy-bit-field: a is not an exact integer".
   5_3.mo:Expected error in mat bitwise-copy-bit-field: "bitwise-copy-bit-field: invalid start index 0.0".
   5_3.mo:Expected error in mat bitwise-copy-bit-field: "bitwise-copy-bit-field: invalid end index 2.0".
---- 1348,1358 ----
+--- 1350,1360 ----
   5_3.mo:Expected error in mat bitwise-bit-field: "bitwise-bit-field: invalid end index -8".
   5_3.mo:Expected error in mat bitwise-bit-field: "bitwise-bit-field: invalid end index 3".
   5_3.mo:Expected error in mat bitwise-bit-field: "bitwise-bit-field: invalid end index <int>".
@@ -1110,7 +1110,7 @@
   5_3.mo:Expected error in mat bitwise-copy-bit-field: "bitwise-copy-bit-field: invalid start index 0.0".
   5_3.mo:Expected error in mat bitwise-copy-bit-field: "bitwise-copy-bit-field: invalid end index 2.0".
 ***************
-*** 1365,1375 ****
+*** 1367,1377 ****
   5_3.mo:Expected error in mat bitwise-copy-bit-field: "bitwise-copy-bit-field: invalid end index 5".
   5_3.mo:Expected error in mat bitwise-copy-bit-field: "bitwise-copy-bit-field: invalid end index <int>".
   5_3.mo:Expected error in mat bitwise-copy-bit-field: "bitwise-copy-bit-field: invalid end index <int>".
@@ -1122,7 +1122,7 @@
   5_3.mo:Expected error in mat bitwise-rotate-bit-field: "bitwise-rotate-bit-field: a is not an exact integer".
   5_3.mo:Expected error in mat bitwise-rotate-bit-field: "bitwise-rotate-bit-field: invalid start index 0.0".
   5_3.mo:Expected error in mat bitwise-rotate-bit-field: "bitwise-rotate-bit-field: invalid end index 2.0".
---- 1365,1375 ----
+--- 1367,1377 ----
   5_3.mo:Expected error in mat bitwise-copy-bit-field: "bitwise-copy-bit-field: invalid end index 5".
   5_3.mo:Expected error in mat bitwise-copy-bit-field: "bitwise-copy-bit-field: invalid end index <int>".
   5_3.mo:Expected error in mat bitwise-copy-bit-field: "bitwise-copy-bit-field: invalid end index <int>".
@@ -1135,7 +1135,7 @@
   5_3.mo:Expected error in mat bitwise-rotate-bit-field: "bitwise-rotate-bit-field: invalid start index 0.0".
   5_3.mo:Expected error in mat bitwise-rotate-bit-field: "bitwise-rotate-bit-field: invalid end index 2.0".
 ***************
-*** 1383,1392 ****
+*** 1385,1394 ****
   5_3.mo:Expected error in mat bitwise-rotate-bit-field: "bitwise-rotate-bit-field: invalid end index 5".
   5_3.mo:Expected error in mat bitwise-rotate-bit-field: "bitwise-rotate-bit-field: invalid end index <int>".
   5_3.mo:Expected error in mat bitwise-rotate-bit-field: "bitwise-rotate-bit-field: invalid end index <int>".
@@ -1146,7 +1146,7 @@
   5_3.mo:Expected error in mat bitwise-bit-field: "bitwise-reverse-bit-field: 35.0 is not an exact integer".
   5_3.mo:Expected error in mat bitwise-bit-field: "bitwise-reverse-bit-field: invalid start index 5.0".
   5_3.mo:Expected error in mat bitwise-bit-field: "bitwise-reverse-bit-field: invalid end index 8.0".
---- 1383,1392 ----
+--- 1385,1394 ----
   5_3.mo:Expected error in mat bitwise-rotate-bit-field: "bitwise-rotate-bit-field: invalid end index 5".
   5_3.mo:Expected error in mat bitwise-rotate-bit-field: "bitwise-rotate-bit-field: invalid end index <int>".
   5_3.mo:Expected error in mat bitwise-rotate-bit-field: "bitwise-rotate-bit-field: invalid end index <int>".
@@ -1158,7 +1158,7 @@
   5_3.mo:Expected error in mat bitwise-bit-field: "bitwise-reverse-bit-field: invalid start index 5.0".
   5_3.mo:Expected error in mat bitwise-bit-field: "bitwise-reverse-bit-field: invalid end index 8.0".
 ***************
-*** 1397,1420 ****
+*** 1399,1422 ****
   5_3.mo:Expected error in mat bitwise-bit-field: "bitwise-reverse-bit-field: invalid end index -8".
   5_3.mo:Expected error in mat bitwise-bit-field: "bitwise-reverse-bit-field: start index 5 is greater than end index 3".
   5_3.mo:Expected error in mat bitwise-bit-field: "bitwise-reverse-bit-field: start index <int> is greater than end index <int>".
@@ -1183,7 +1183,7 @@
   5_3.mo:Expected error in mat bitwise-first-bit-set: "bitwise-first-bit-set: 3.0 is not an exact integer".
   5_3.mo:Expected error in mat bitwise-first-bit-set: "bitwise-first-bit-set: a is not an exact integer".
   5_3.mo:Expected error in mat $quotient-remainder: "incorrect number of arguments to #<procedure $quotient-remainder>".
---- 1397,1420 ----
+--- 1399,1422 ----
   5_3.mo:Expected error in mat bitwise-bit-field: "bitwise-reverse-bit-field: invalid end index -8".
   5_3.mo:Expected error in mat bitwise-bit-field: "bitwise-reverse-bit-field: start index 5 is greater than end index 3".
   5_3.mo:Expected error in mat bitwise-bit-field: "bitwise-reverse-bit-field: start index <int> is greater than end index <int>".
@@ -1209,7 +1209,7 @@
   5_3.mo:Expected error in mat bitwise-first-bit-set: "bitwise-first-bit-set: a is not an exact integer".
   5_3.mo:Expected error in mat $quotient-remainder: "incorrect number of arguments to #<procedure $quotient-remainder>".
 ***************
-*** 1540,1595 ****
+*** 1542,1597 ****
   5_3.mo:Expected error in mat bitwise-xor: "bitwise-xor: 3.4-2.3i is not an exact integer".
   5_3.mo:Expected error in mat bitwise-xor: "bitwise-xor: 3.4-2.3i is not an exact integer".
   5_3.mo:Expected error in mat bitwise-xor: "bitwise-xor: 3.0 is not an exact integer".
@@ -1266,7 +1266,7 @@
   5_3.mo:Expected error in mat real->flonum: "real->flonum: a is not a real number".
   5_3.mo:Expected error in mat real->flonum: "real->flonum: 3+4i is not a real number".
   5_3.mo:Expected error in mat div-and-mod: "div-and-mod: undefined for 0".
---- 1540,1595 ----
+--- 1542,1597 ----
   5_3.mo:Expected error in mat bitwise-xor: "bitwise-xor: 3.4-2.3i is not an exact integer".
   5_3.mo:Expected error in mat bitwise-xor: "bitwise-xor: 3.4-2.3i is not an exact integer".
   5_3.mo:Expected error in mat bitwise-xor: "bitwise-xor: 3.0 is not an exact integer".
@@ -1324,7 +1324,7 @@
   5_3.mo:Expected error in mat real->flonum: "real->flonum: 3+4i is not a real number".
   5_3.mo:Expected error in mat div-and-mod: "div-and-mod: undefined for 0".
 ***************
-*** 1622,1782 ****
+*** 1624,1784 ****
   5_3.mo:Expected error in mat div0-and-mod0: "mod0: undefined for 0".
   5_3.mo:Expected error in mat div0-and-mod0: "mod0: undefined for a".
   5_3.mo:Expected error in mat div0-and-mod0: "mod0: undefined for (a)".
@@ -1486,7 +1486,7 @@
   5_4.mo:Expected error in mat integer->char: "integer->char: a is not a valid unicode scalar value".
   5_4.mo:Expected error in mat integer->char: "integer->char: #f is not a valid unicode scalar value".
   5_4.mo:Expected error in mat integer->char: "integer->char: #\a is not a valid unicode scalar value".
---- 1622,1782 ----
+--- 1624,1784 ----
   5_3.mo:Expected error in mat div0-and-mod0: "mod0: undefined for 0".
   5_3.mo:Expected error in mat div0-and-mod0: "mod0: undefined for a".
   5_3.mo:Expected error in mat div0-and-mod0: "mod0: undefined for (a)".
@@ -1649,7 +1649,7 @@
   5_4.mo:Expected error in mat integer->char: "integer->char: #f is not a valid unicode scalar value".
   5_4.mo:Expected error in mat integer->char: "integer->char: #\a is not a valid unicode scalar value".
 ***************
-*** 1795,1807 ****
+*** 1797,1809 ****
   5_4.mo:Expected error in mat integer->char: "integer->char: 1114112 is not a valid unicode scalar value".
   5_4.mo:Expected error in mat integer->char: "integer->char: 1179648 is not a valid unicode scalar value".
   5_4.mo:Expected error in mat integer->char: "integer->char: <int> is not a valid unicode scalar value".
@@ -1663,7 +1663,7 @@
   5_4.mo:Expected error in mat string-for-each: "string-for-each: "" is not a procedure".
   5_4.mo:Expected error in mat string-for-each: "string-for-each: "" is not a procedure".
   5_4.mo:Expected error in mat string-for-each: "string-for-each: "" is not a procedure".
---- 1795,1807 ----
+--- 1797,1809 ----
   5_4.mo:Expected error in mat integer->char: "integer->char: 1114112 is not a valid unicode scalar value".
   5_4.mo:Expected error in mat integer->char: "integer->char: 1179648 is not a valid unicode scalar value".
   5_4.mo:Expected error in mat integer->char: "integer->char: <int> is not a valid unicode scalar value".
@@ -1678,7 +1678,7 @@
   5_4.mo:Expected error in mat string-for-each: "string-for-each: "" is not a procedure".
   5_4.mo:Expected error in mat string-for-each: "string-for-each: "" is not a procedure".
 ***************
-*** 1816,1961 ****
+*** 1818,1963 ****
   5_4.mo:Expected error in mat string-for-each: "string-for-each: lengths of input string "" and "x" differ".
   5_4.mo:Expected error in mat string-for-each: "string-for-each: lengths of input string "y" and "" differ".
   5_4.mo:Expected error in mat string-for-each: "string-for-each: lengths of input string "y" and "" differ".
@@ -1825,7 +1825,7 @@
   5_5.mo:Expected error in mat r6rs:string>=?/r6rs:string-ci>=?: "string-ci>=?: a is not a string".
   5_5.mo:Expected error in mat r6rs:string>=?/r6rs:string-ci>=?: "string-ci>=?: a is not a string".
   5_5.mo:Expected error in mat r6rs:string>=?/r6rs:string-ci>=?: "string-ci>=?: a is not a string".
---- 1816,1961 ----
+--- 1818,1963 ----
   5_4.mo:Expected error in mat string-for-each: "string-for-each: lengths of input string "" and "x" differ".
   5_4.mo:Expected error in mat string-for-each: "string-for-each: lengths of input string "y" and "" differ".
   5_4.mo:Expected error in mat string-for-each: "string-for-each: lengths of input string "y" and "" differ".
@@ -1973,14 +1973,14 @@
   5_5.mo:Expected error in mat r6rs:string>=?/r6rs:string-ci>=?: "string-ci>=?: a is not a string".
   5_5.mo:Expected error in mat r6rs:string>=?/r6rs:string-ci>=?: "string-ci>=?: a is not a string".
 ***************
-*** 1963,2001 ****
+*** 1965,2003 ****
   5_5.mo:Expected error in mat string: "string: a is not a character".
   5_5.mo:Expected error in mat string: "string: a is not a character".
   5_5.mo:Expected error in mat string: "string: a is not a character".
 ! 5_5.mo:Expected error in mat make-string: "incorrect argument count in call (make-string)".
 ! 5_5.mo:Expected error in mat make-string: "incorrect argument count in call (make-string 2 #\a #\b)".
   5_5.mo:Expected error in mat make-string: "make-string: a is not a character".
-  5_5.mo:Expected error in mat make-string: "make-string: a is not a nonnegative fixnum".
+  5_5.mo:Expected error in mat make-string: "make-string: a is not a valid string length".
 ! 5_5.mo:Expected error in mat string-length: "incorrect argument count in call (string-length)".
 ! 5_5.mo:Expected error in mat string-length: "incorrect argument count in call (string-length "hi" "there")".
   5_5.mo:Expected error in mat string-length: "string-length: a is not a string".
@@ -1995,7 +1995,7 @@
 ! 5_5.mo:Expected error in mat string-set!: "incorrect argument count in call (string-set! "hi")".
 ! 5_5.mo:Expected error in mat string-set!: "incorrect argument count in call (string-set! "hi" 1)".
 ! 5_5.mo:Expected error in mat string-set!: "incorrect argument count in call (string-set! "hi" 3 #\a #\b)".
-  5_5.mo:Expected error in mat string-set!: "string-set!: a is not a string".
+  5_5.mo:Expected error in mat string-set!: "string-set!: a is not a mutable string".
   5_5.mo:Expected error in mat string-set!: "string-set!: a is not a valid index for "hi"".
   5_5.mo:Expected error in mat string-set!: "string-set!: 3 is not a valid index for "hi"".
   5_5.mo:Expected error in mat string-set!: "string-set!: -1 is not a valid index for "hi"".
@@ -2011,16 +2011,16 @@
 ! 5_5.mo:Expected error in mat string-copy!: "incorrect argument count in call (string-copy! $s2 3 $s1 1)".
 ! 5_5.mo:Expected error in mat string-copy!: "incorrect argument count in call (string-copy! $s2 3 $s1 1 2 ...)".
   5_5.mo:Expected error in mat string-copy!: "string-copy!: 0 is not a string".
-  5_5.mo:Expected error in mat string-copy!: "string-copy!: #vu8(1 2 3) is not a string".
+  5_5.mo:Expected error in mat string-copy!: "string-copy!: #vu8(1 2 3) is not a mutable string".
   5_5.mo:Expected error in mat string-copy!: "string-copy!: invalid start value -1".
---- 1963,2001 ----
+--- 1965,2003 ----
   5_5.mo:Expected error in mat string: "string: a is not a character".
   5_5.mo:Expected error in mat string: "string: a is not a character".
   5_5.mo:Expected error in mat string: "string: a is not a character".
 ! 5_5.mo:Expected error in mat make-string: "incorrect number of arguments to #<procedure make-string>".
 ! 5_5.mo:Expected error in mat make-string: "incorrect number of arguments to #<procedure make-string>".
   5_5.mo:Expected error in mat make-string: "make-string: a is not a character".
-  5_5.mo:Expected error in mat make-string: "make-string: a is not a nonnegative fixnum".
+  5_5.mo:Expected error in mat make-string: "make-string: a is not a valid string length".
 ! 5_5.mo:Expected error in mat string-length: "incorrect number of arguments to #<procedure string-length>".
 ! 5_5.mo:Expected error in mat string-length: "incorrect number of arguments to #<procedure string-length>".
   5_5.mo:Expected error in mat string-length: "string-length: a is not a string".
@@ -2035,7 +2035,7 @@
 ! 5_5.mo:Expected error in mat string-set!: "incorrect number of arguments to #<procedure string-set!>".
 ! 5_5.mo:Expected error in mat string-set!: "incorrect number of arguments to #<procedure string-set!>".
 ! 5_5.mo:Expected error in mat string-set!: "incorrect number of arguments to #<procedure string-set!>".
-  5_5.mo:Expected error in mat string-set!: "string-set!: a is not a string".
+  5_5.mo:Expected error in mat string-set!: "string-set!: a is not a mutable string".
   5_5.mo:Expected error in mat string-set!: "string-set!: a is not a valid index for "hi"".
   5_5.mo:Expected error in mat string-set!: "string-set!: 3 is not a valid index for "hi"".
   5_5.mo:Expected error in mat string-set!: "string-set!: -1 is not a valid index for "hi"".
@@ -2051,31 +2051,31 @@
 ! 5_5.mo:Expected error in mat string-copy!: "incorrect number of arguments to #<procedure string-copy!>".
 ! 5_5.mo:Expected error in mat string-copy!: "incorrect number of arguments to #<procedure string-copy!>".
   5_5.mo:Expected error in mat string-copy!: "string-copy!: 0 is not a string".
-  5_5.mo:Expected error in mat string-copy!: "string-copy!: #vu8(1 2 3) is not a string".
+  5_5.mo:Expected error in mat string-copy!: "string-copy!: #vu8(1 2 3) is not a mutable string".
   5_5.mo:Expected error in mat string-copy!: "string-copy!: invalid start value -1".
 ***************
-*** 2019,2027 ****
+*** 2021,2029 ****
   5_5.mo:Expected error in mat string-copy!: "string-copy!: index 4 + count 1 is beyond the end of "1234"".
   5_5.mo:Expected error in mat string-copy!: "string-copy!: index 0 + count 500 is beyond the end of "abcdefghi"".
   5_5.mo:Expected error in mat string-copy!: "string-copy!: index 500 + count 0 is beyond the end of "abcdefghi"".
 ! 5_5.mo:Expected error in mat string-truncate!: "incorrect argument count in call (string-truncate!)".
 ! 5_5.mo:Expected error in mat string-truncate!: "incorrect argument count in call (string-truncate! $s)".
 ! 5_5.mo:Expected error in mat string-truncate!: "incorrect argument count in call (string-truncate! $s 3 15)".
-  5_5.mo:Expected error in mat string-truncate!: "string-truncate!: 0 is not a string".
-  5_5.mo:Expected error in mat string-truncate!: "string-truncate!: #vu8(1 2 3) is not a string".
+  5_5.mo:Expected error in mat string-truncate!: "string-truncate!: 0 is not a mutable string".
+  5_5.mo:Expected error in mat string-truncate!: "string-truncate!: #vu8(1 2 3) is not a mutable string".
   5_5.mo:Expected error in mat string-truncate!: "string-truncate!: invalid new length -1 for "abcdefghi"".
---- 2019,2027 ----
+--- 2021,2029 ----
   5_5.mo:Expected error in mat string-copy!: "string-copy!: index 4 + count 1 is beyond the end of "1234"".
   5_5.mo:Expected error in mat string-copy!: "string-copy!: index 0 + count 500 is beyond the end of "abcdefghi"".
   5_5.mo:Expected error in mat string-copy!: "string-copy!: index 500 + count 0 is beyond the end of "abcdefghi"".
 ! 5_5.mo:Expected error in mat string-truncate!: "incorrect number of arguments to #<procedure string-truncate!>".
 ! 5_5.mo:Expected error in mat string-truncate!: "incorrect number of arguments to #<procedure string-truncate!>".
 ! 5_5.mo:Expected error in mat string-truncate!: "incorrect number of arguments to #<procedure string-truncate!>".
-  5_5.mo:Expected error in mat string-truncate!: "string-truncate!: 0 is not a string".
-  5_5.mo:Expected error in mat string-truncate!: "string-truncate!: #vu8(1 2 3) is not a string".
+  5_5.mo:Expected error in mat string-truncate!: "string-truncate!: 0 is not a mutable string".
+  5_5.mo:Expected error in mat string-truncate!: "string-truncate!: #vu8(1 2 3) is not a mutable string".
   5_5.mo:Expected error in mat string-truncate!: "string-truncate!: invalid new length -1 for "abcdefghi"".
 ***************
-*** 2033,2080 ****
+*** 2035,2087 ****
   5_5.mo:Expected error in mat string-append: "string-append: b is not a string".
   5_5.mo:Expected error in mat string-append: "string-append: b is not a string".
   5_5.mo:Expected error in mat string-append: "string-copy: a is not a string".
@@ -2093,14 +2093,14 @@
 ! 5_5.mo:Expected error in mat string-fill!: "incorrect argument count in call (string-fill! "hi")".
 ! 5_5.mo:Expected error in mat string-fill!: "incorrect argument count in call (string-fill! "hi" #\a #\b)".
   5_5.mo:Expected error in mat string-fill!: "string-fill!: a is not a character".
-  5_5.mo:Expected error in mat string-fill!: "string-fill!: a is not a string".
+  5_5.mo:Expected error in mat string-fill!: "string-fill!: a is not a mutable string".
 ! 5_5.mo:Expected error in mat substring-fill!: "incorrect argument count in call (substring-fill!)".
 ! 5_5.mo:Expected error in mat substring-fill!: "incorrect argument count in call (substring-fill! "hi")".
 ! 5_5.mo:Expected error in mat substring-fill!: "incorrect argument count in call (substring-fill! "hi" 0)".
 ! 5_5.mo:Expected error in mat substring-fill!: "incorrect argument count in call (substring-fill! "hi" 0 2)".
   5_5.mo:Expected error in mat substring-fill!: "substring-fill!: 0 and 3 are not valid start/end indices for "hi"".
   5_5.mo:Expected error in mat substring-fill!: "substring-fill!: -1 and 3 are not valid start/end indices for "hi"".
-  5_5.mo:Expected error in mat substring-fill!: "substring-fill!: a is not a string".
+  5_5.mo:Expected error in mat substring-fill!: "substring-fill!: a is not a mutable string".
   5_5.mo:Expected error in mat substring-fill!: "substring-fill!: 0 and a are not valid start/end indices for "hi"".
   5_5.mo:Expected error in mat substring-fill!: "substring-fill!: 1 and 0 are not valid start/end indices for "hi"".
 ! 5_5.mo:Expected error in mat list->string: "incorrect argument count in call (list->string)".
@@ -2112,6 +2112,11 @@
 ! 5_5.mo:Expected error in mat string->list: "incorrect argument count in call (string->list)".
 ! 5_5.mo:Expected error in mat string->list: "incorrect argument count in call (string->list "ab" "cd")".
   5_5.mo:Expected error in mat string->list: "string->list: a is not a string".
+  5_5.mo:Expected error in mat string->immutable-string: "string-set!: "abc" is not a mutable string".
+  5_5.mo:Expected error in mat string->immutable-string: "string-fill!: "abc" is not a mutable string".
+  5_5.mo:Expected error in mat string->immutable-string: "substring-fill!: "abc" is not a mutable string".
+  5_5.mo:Expected error in mat string->immutable-string: "string-copy!: "abc" is not a mutable string".
+  5_5.mo:Expected error in mat string->immutable-string: "string-truncate!: "abc" is not a mutable string".
 ! bytevector.mo:Expected error in mat native-endianness: "incorrect argument count in call (native-endianness (quote big))".
   bytevector.mo:Expected error in mat endianness: "invalid endianness spam".
   bytevector.mo:Expected error in mat endianness: "invalid endianness (quote big)".
@@ -2121,10 +2126,10 @@
   bytevector.mo:Expected error in mat endianness: "invalid syntax (endianness big little)".
 ! bytevector.mo:Expected error in mat make-bytevector: "incorrect argument count in call (make-bytevector)".
 ! bytevector.mo:Expected error in mat make-bytevector: "incorrect argument count in call (make-bytevector 0 0 0)".
-  bytevector.mo:Expected error in mat make-bytevector: "make-bytevector: -1 is not a nonnegative fixnum".
-  bytevector.mo:Expected error in mat make-bytevector: "make-bytevector: -1 is not a nonnegative fixnum".
-  bytevector.mo:Expected error in mat make-bytevector: "make-bytevector: <int> is not a nonnegative fixnum".
---- 2033,2080 ----
+  bytevector.mo:Expected error in mat make-bytevector: "make-bytevector: -1 is not a valid bytevector length".
+  bytevector.mo:Expected error in mat make-bytevector: "make-bytevector: -1 is not a valid bytevector length".
+  bytevector.mo:Expected error in mat make-bytevector: "make-bytevector: <int> is not a valid bytevector length".
+--- 2035,2087 ----
   5_5.mo:Expected error in mat string-append: "string-append: b is not a string".
   5_5.mo:Expected error in mat string-append: "string-append: b is not a string".
   5_5.mo:Expected error in mat string-append: "string-copy: a is not a string".
@@ -2142,14 +2147,14 @@
 ! 5_5.mo:Expected error in mat string-fill!: "incorrect number of arguments to #<procedure string-fill!>".
 ! 5_5.mo:Expected error in mat string-fill!: "incorrect number of arguments to #<procedure string-fill!>".
   5_5.mo:Expected error in mat string-fill!: "string-fill!: a is not a character".
-  5_5.mo:Expected error in mat string-fill!: "string-fill!: a is not a string".
+  5_5.mo:Expected error in mat string-fill!: "string-fill!: a is not a mutable string".
 ! 5_5.mo:Expected error in mat substring-fill!: "incorrect number of arguments to #<procedure substring-fill!>".
 ! 5_5.mo:Expected error in mat substring-fill!: "incorrect number of arguments to #<procedure substring-fill!>".
 ! 5_5.mo:Expected error in mat substring-fill!: "incorrect number of arguments to #<procedure substring-fill!>".
 ! 5_5.mo:Expected error in mat substring-fill!: "incorrect number of arguments to #<procedure substring-fill!>".
   5_5.mo:Expected error in mat substring-fill!: "substring-fill!: 0 and 3 are not valid start/end indices for "hi"".
   5_5.mo:Expected error in mat substring-fill!: "substring-fill!: -1 and 3 are not valid start/end indices for "hi"".
-  5_5.mo:Expected error in mat substring-fill!: "substring-fill!: a is not a string".
+  5_5.mo:Expected error in mat substring-fill!: "substring-fill!: a is not a mutable string".
   5_5.mo:Expected error in mat substring-fill!: "substring-fill!: 0 and a are not valid start/end indices for "hi"".
   5_5.mo:Expected error in mat substring-fill!: "substring-fill!: 1 and 0 are not valid start/end indices for "hi"".
 ! 5_5.mo:Expected error in mat list->string: "incorrect number of arguments to #<procedure list->string>".
@@ -2161,6 +2166,11 @@
 ! 5_5.mo:Expected error in mat string->list: "incorrect number of arguments to #<procedure string->list>".
 ! 5_5.mo:Expected error in mat string->list: "incorrect number of arguments to #<procedure string->list>".
   5_5.mo:Expected error in mat string->list: "string->list: a is not a string".
+  5_5.mo:Expected error in mat string->immutable-string: "string-set!: "abc" is not a mutable string".
+  5_5.mo:Expected error in mat string->immutable-string: "string-fill!: "abc" is not a mutable string".
+  5_5.mo:Expected error in mat string->immutable-string: "substring-fill!: "abc" is not a mutable string".
+  5_5.mo:Expected error in mat string->immutable-string: "string-copy!: "abc" is not a mutable string".
+  5_5.mo:Expected error in mat string->immutable-string: "string-truncate!: "abc" is not a mutable string".
 ! bytevector.mo:Expected error in mat native-endianness: "incorrect number of arguments to #<procedure native-endianness>".
   bytevector.mo:Expected error in mat endianness: "invalid endianness spam".
   bytevector.mo:Expected error in mat endianness: "invalid endianness (quote big)".
@@ -2170,11 +2180,11 @@
   bytevector.mo:Expected error in mat endianness: "invalid syntax (endianness big little)".
 ! bytevector.mo:Expected error in mat make-bytevector: "incorrect number of arguments to #<procedure make-bytevector>".
 ! bytevector.mo:Expected error in mat make-bytevector: "incorrect number of arguments to #<procedure make-bytevector>".
-  bytevector.mo:Expected error in mat make-bytevector: "make-bytevector: -1 is not a nonnegative fixnum".
-  bytevector.mo:Expected error in mat make-bytevector: "make-bytevector: -1 is not a nonnegative fixnum".
-  bytevector.mo:Expected error in mat make-bytevector: "make-bytevector: <int> is not a nonnegative fixnum".
+  bytevector.mo:Expected error in mat make-bytevector: "make-bytevector: -1 is not a valid bytevector length".
+  bytevector.mo:Expected error in mat make-bytevector: "make-bytevector: -1 is not a valid bytevector length".
+  bytevector.mo:Expected error in mat make-bytevector: "make-bytevector: <int> is not a valid bytevector length".
 ***************
-*** 2091,2120 ****
+*** 2098,2127 ****
   bytevector.mo:Expected error in mat bytevector: "bytevector: invalid value -500".
   bytevector.mo:Expected error in mat bytevector: "bytevector: invalid value 1e100".
   bytevector.mo:Expected error in mat bytevector: "bytevector: invalid value 10000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000".
@@ -2202,10 +2212,10 @@
 ! bytevector.mo:Expected error in mat bytevector-s8-set!: "incorrect argument count in call (bytevector-s8-set! $v1)".
 ! bytevector.mo:Expected error in mat bytevector-s8-set!: "incorrect argument count in call (bytevector-s8-set! $v1 2)".
 ! bytevector.mo:Expected error in mat bytevector-s8-set!: "incorrect argument count in call (bytevector-s8-set! $v1 2 3 4)".
-  bytevector.mo:Expected error in mat bytevector-s8-set!: "bytevector-s8-set!: (3 4 5) is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-s8-set!: "bytevector-s8-set!: (3 4 5) is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-s8-set!: "bytevector-s8-set!: (3 4 5) is not a mutable bytevector".
+  bytevector.mo:Expected error in mat bytevector-s8-set!: "bytevector-s8-set!: (3 4 5) is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-s8-set!: "bytevector-s8-set!: 3 is not a valid index for #vu8(3 4 5)".
---- 2091,2120 ----
+--- 2098,2127 ----
   bytevector.mo:Expected error in mat bytevector: "bytevector: invalid value -500".
   bytevector.mo:Expected error in mat bytevector: "bytevector: invalid value 1e100".
   bytevector.mo:Expected error in mat bytevector: "bytevector: invalid value 10000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000".
@@ -2233,11 +2243,11 @@
 ! bytevector.mo:Expected error in mat bytevector-s8-set!: "incorrect number of arguments to #<procedure bytevector-s8-set!>".
 ! bytevector.mo:Expected error in mat bytevector-s8-set!: "incorrect number of arguments to #<procedure bytevector-s8-set!>".
 ! bytevector.mo:Expected error in mat bytevector-s8-set!: "incorrect number of arguments to #<procedure bytevector-s8-set!>".
-  bytevector.mo:Expected error in mat bytevector-s8-set!: "bytevector-s8-set!: (3 4 5) is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-s8-set!: "bytevector-s8-set!: (3 4 5) is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-s8-set!: "bytevector-s8-set!: (3 4 5) is not a mutable bytevector".
+  bytevector.mo:Expected error in mat bytevector-s8-set!: "bytevector-s8-set!: (3 4 5) is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-s8-set!: "bytevector-s8-set!: 3 is not a valid index for #vu8(3 4 5)".
 ***************
-*** 2123,2132 ****
+*** 2130,2139 ****
   bytevector.mo:Expected error in mat bytevector-s8-set!: "bytevector-s8-set!: invalid value -129".
   bytevector.mo:Expected error in mat bytevector-s8-set!: "bytevector-s8-set!: invalid value 128".
   bytevector.mo:Expected error in mat bytevector-s8-set!: "bytevector-s8-set!: invalid value d".
@@ -2245,10 +2255,10 @@
 ! bytevector.mo:Expected error in mat bytevector-u8-set!: "incorrect argument count in call (bytevector-u8-set! $v1)".
 ! bytevector.mo:Expected error in mat bytevector-u8-set!: "incorrect argument count in call (bytevector-u8-set! $v1 2)".
 ! bytevector.mo:Expected error in mat bytevector-u8-set!: "incorrect argument count in call (bytevector-u8-set! $v1 2 3 4)".
-  bytevector.mo:Expected error in mat bytevector-u8-set!: "bytevector-u8-set!: (3 4 5) is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-u8-set!: "bytevector-u8-set!: (3 4 5) is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-u8-set!: "bytevector-u8-set!: (3 4 5) is not a mutable bytevector".
+  bytevector.mo:Expected error in mat bytevector-u8-set!: "bytevector-u8-set!: (3 4 5) is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-u8-set!: "bytevector-u8-set!: 3 is not a valid index for #vu8(3 4 5)".
---- 2123,2132 ----
+--- 2130,2139 ----
   bytevector.mo:Expected error in mat bytevector-s8-set!: "bytevector-s8-set!: invalid value -129".
   bytevector.mo:Expected error in mat bytevector-s8-set!: "bytevector-s8-set!: invalid value 128".
   bytevector.mo:Expected error in mat bytevector-s8-set!: "bytevector-s8-set!: invalid value d".
@@ -2256,11 +2266,11 @@
 ! bytevector.mo:Expected error in mat bytevector-u8-set!: "incorrect number of arguments to #<procedure bytevector-u8-set!>".
 ! bytevector.mo:Expected error in mat bytevector-u8-set!: "incorrect number of arguments to #<procedure bytevector-u8-set!>".
 ! bytevector.mo:Expected error in mat bytevector-u8-set!: "incorrect number of arguments to #<procedure bytevector-u8-set!>".
-  bytevector.mo:Expected error in mat bytevector-u8-set!: "bytevector-u8-set!: (3 4 5) is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-u8-set!: "bytevector-u8-set!: (3 4 5) is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-u8-set!: "bytevector-u8-set!: (3 4 5) is not a mutable bytevector".
+  bytevector.mo:Expected error in mat bytevector-u8-set!: "bytevector-u8-set!: (3 4 5) is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-u8-set!: "bytevector-u8-set!: 3 is not a valid index for #vu8(3 4 5)".
 ***************
-*** 2135,2143 ****
+*** 2142,2150 ****
   bytevector.mo:Expected error in mat bytevector-u8-set!: "bytevector-u8-set!: invalid value -1".
   bytevector.mo:Expected error in mat bytevector-u8-set!: "bytevector-u8-set!: invalid value 256".
   bytevector.mo:Expected error in mat bytevector-u8-set!: "bytevector-u8-set!: invalid value d".
@@ -2270,7 +2280,7 @@
   bytevector.mo:Expected error in mat bytevector-s16-native-ref: "bytevector-s16-native-ref: #(3 252 5) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-s16-native-ref: "bytevector-s16-native-ref: #(3 252 5) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-s16-native-ref: "bytevector-s16-native-ref: invalid index -1 for bytevector #vu8(3 252 5)".
---- 2135,2143 ----
+--- 2142,2150 ----
   bytevector.mo:Expected error in mat bytevector-u8-set!: "bytevector-u8-set!: invalid value -1".
   bytevector.mo:Expected error in mat bytevector-u8-set!: "bytevector-u8-set!: invalid value 256".
   bytevector.mo:Expected error in mat bytevector-u8-set!: "bytevector-u8-set!: invalid value d".
@@ -2281,7 +2291,7 @@
   bytevector.mo:Expected error in mat bytevector-s16-native-ref: "bytevector-s16-native-ref: #(3 252 5) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-s16-native-ref: "bytevector-s16-native-ref: invalid index -1 for bytevector #vu8(3 252 5)".
 ***************
-*** 2145,2153 ****
+*** 2152,2160 ****
   bytevector.mo:Expected error in mat bytevector-s16-native-ref: "bytevector-s16-native-ref: invalid index 2 for bytevector #vu8(3 252 5)".
   bytevector.mo:Expected error in mat bytevector-s16-native-ref: "bytevector-s16-native-ref: invalid index 3 for bytevector #vu8(3 252 5)".
   bytevector.mo:Expected error in mat bytevector-s16-native-ref: "bytevector-s16-native-ref: invalid index 4.0 for bytevector #vu8(3 252 5)".
@@ -2291,7 +2301,7 @@
   bytevector.mo:Expected error in mat bytevector-u16-native-ref: "bytevector-u16-native-ref: #(3 252 5) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-u16-native-ref: "bytevector-u16-native-ref: #(3 252 5) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-u16-native-ref: "bytevector-u16-native-ref: invalid index -1 for bytevector #vu8(3 252 5)".
---- 2145,2153 ----
+--- 2152,2160 ----
   bytevector.mo:Expected error in mat bytevector-s16-native-ref: "bytevector-s16-native-ref: invalid index 2 for bytevector #vu8(3 252 5)".
   bytevector.mo:Expected error in mat bytevector-s16-native-ref: "bytevector-s16-native-ref: invalid index 3 for bytevector #vu8(3 252 5)".
   bytevector.mo:Expected error in mat bytevector-s16-native-ref: "bytevector-s16-native-ref: invalid index 4.0 for bytevector #vu8(3 252 5)".
@@ -2302,7 +2312,7 @@
   bytevector.mo:Expected error in mat bytevector-u16-native-ref: "bytevector-u16-native-ref: #(3 252 5) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-u16-native-ref: "bytevector-u16-native-ref: invalid index -1 for bytevector #vu8(3 252 5)".
 ***************
-*** 2155,2164 ****
+*** 2162,2171 ****
   bytevector.mo:Expected error in mat bytevector-u16-native-ref: "bytevector-u16-native-ref: invalid index 2 for bytevector #vu8(3 252 5)".
   bytevector.mo:Expected error in mat bytevector-u16-native-ref: "bytevector-u16-native-ref: invalid index 3 for bytevector #vu8(3 252 5)".
   bytevector.mo:Expected error in mat bytevector-u16-native-ref: "bytevector-u16-native-ref: invalid index 4.0 for bytevector #vu8(3 252 5)".
@@ -2310,10 +2320,10 @@
 ! bytevector.mo:Expected error in mat bytevector-s16-native-set!: "incorrect argument count in call (bytevector-s16-native-set! $v1)".
 ! bytevector.mo:Expected error in mat bytevector-s16-native-set!: "incorrect argument count in call (bytevector-s16-native-set! $v1 0)".
 ! bytevector.mo:Expected error in mat bytevector-s16-native-set!: "incorrect argument count in call (bytevector-s16-native-set! $v1 0 0 15)".
-  bytevector.mo:Expected error in mat bytevector-s16-native-set!: "bytevector-s16-native-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-s16-native-set!: "bytevector-s16-native-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-s16-native-set!: "bytevector-s16-native-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+  bytevector.mo:Expected error in mat bytevector-s16-native-set!: "bytevector-s16-native-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-s16-native-set!: "bytevector-s16-native-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
---- 2155,2164 ----
+--- 2162,2171 ----
   bytevector.mo:Expected error in mat bytevector-u16-native-ref: "bytevector-u16-native-ref: invalid index 2 for bytevector #vu8(3 252 5)".
   bytevector.mo:Expected error in mat bytevector-u16-native-ref: "bytevector-u16-native-ref: invalid index 3 for bytevector #vu8(3 252 5)".
   bytevector.mo:Expected error in mat bytevector-u16-native-ref: "bytevector-u16-native-ref: invalid index 4.0 for bytevector #vu8(3 252 5)".
@@ -2321,11 +2331,11 @@
 ! bytevector.mo:Expected error in mat bytevector-s16-native-set!: "incorrect number of arguments to #<procedure bytevector-s16-native-set!>".
 ! bytevector.mo:Expected error in mat bytevector-s16-native-set!: "incorrect number of arguments to #<procedure bytevector-s16-native-set!>".
 ! bytevector.mo:Expected error in mat bytevector-s16-native-set!: "incorrect number of arguments to #<procedure bytevector-s16-native-set!>".
-  bytevector.mo:Expected error in mat bytevector-s16-native-set!: "bytevector-s16-native-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-s16-native-set!: "bytevector-s16-native-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-s16-native-set!: "bytevector-s16-native-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+  bytevector.mo:Expected error in mat bytevector-s16-native-set!: "bytevector-s16-native-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-s16-native-set!: "bytevector-s16-native-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 ***************
-*** 2172,2181 ****
+*** 2179,2188 ****
   bytevector.mo:Expected error in mat bytevector-s16-native-set!: "bytevector-s16-native-set!: invalid value 32768".
   bytevector.mo:Expected error in mat bytevector-s16-native-set!: "bytevector-s16-native-set!: invalid value -32769".
   bytevector.mo:Expected error in mat bytevector-s16-native-set!: "bytevector-s16-native-set!: invalid value "hello"".
@@ -2333,10 +2343,10 @@
 ! bytevector.mo:Expected error in mat bytevector-u16-native-set!: "incorrect argument count in call (bytevector-u16-native-set! $v1)".
 ! bytevector.mo:Expected error in mat bytevector-u16-native-set!: "incorrect argument count in call (bytevector-u16-native-set! $v1 0)".
 ! bytevector.mo:Expected error in mat bytevector-u16-native-set!: "incorrect argument count in call (bytevector-u16-native-set! $v1 0 0 15)".
-  bytevector.mo:Expected error in mat bytevector-u16-native-set!: "bytevector-u16-native-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-u16-native-set!: "bytevector-u16-native-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-u16-native-set!: "bytevector-u16-native-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+  bytevector.mo:Expected error in mat bytevector-u16-native-set!: "bytevector-u16-native-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-u16-native-set!: "bytevector-u16-native-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
---- 2172,2181 ----
+--- 2179,2188 ----
   bytevector.mo:Expected error in mat bytevector-s16-native-set!: "bytevector-s16-native-set!: invalid value 32768".
   bytevector.mo:Expected error in mat bytevector-s16-native-set!: "bytevector-s16-native-set!: invalid value -32769".
   bytevector.mo:Expected error in mat bytevector-s16-native-set!: "bytevector-s16-native-set!: invalid value "hello"".
@@ -2344,11 +2354,11 @@
 ! bytevector.mo:Expected error in mat bytevector-u16-native-set!: "incorrect number of arguments to #<procedure bytevector-u16-native-set!>".
 ! bytevector.mo:Expected error in mat bytevector-u16-native-set!: "incorrect number of arguments to #<procedure bytevector-u16-native-set!>".
 ! bytevector.mo:Expected error in mat bytevector-u16-native-set!: "incorrect number of arguments to #<procedure bytevector-u16-native-set!>".
-  bytevector.mo:Expected error in mat bytevector-u16-native-set!: "bytevector-u16-native-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-u16-native-set!: "bytevector-u16-native-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-u16-native-set!: "bytevector-u16-native-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+  bytevector.mo:Expected error in mat bytevector-u16-native-set!: "bytevector-u16-native-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-u16-native-set!: "bytevector-u16-native-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 ***************
-*** 2189,2197 ****
+*** 2196,2204 ****
   bytevector.mo:Expected error in mat bytevector-u16-native-set!: "bytevector-u16-native-set!: invalid value 65536".
   bytevector.mo:Expected error in mat bytevector-u16-native-set!: "bytevector-u16-native-set!: invalid value -1".
   bytevector.mo:Expected error in mat bytevector-u16-native-set!: "bytevector-u16-native-set!: invalid value "hello"".
@@ -2358,7 +2368,7 @@
   bytevector.mo:Expected error in mat bytevector-s16-ref: "bytevector-s16-ref: #(3 252 5) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-s16-ref: "bytevector-s16-ref: #(3 252 5) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-s16-ref: "bytevector-s16-ref: invalid index -1 for bytevector #vu8(3 252 5)".
---- 2189,2197 ----
+--- 2196,2204 ----
   bytevector.mo:Expected error in mat bytevector-u16-native-set!: "bytevector-u16-native-set!: invalid value 65536".
   bytevector.mo:Expected error in mat bytevector-u16-native-set!: "bytevector-u16-native-set!: invalid value -1".
   bytevector.mo:Expected error in mat bytevector-u16-native-set!: "bytevector-u16-native-set!: invalid value "hello"".
@@ -2369,7 +2379,7 @@
   bytevector.mo:Expected error in mat bytevector-s16-ref: "bytevector-s16-ref: #(3 252 5) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-s16-ref: "bytevector-s16-ref: invalid index -1 for bytevector #vu8(3 252 5)".
 ***************
-*** 2201,2209 ****
+*** 2208,2216 ****
   bytevector.mo:Expected error in mat bytevector-s16-ref: "bytevector-s16-ref: unrecognized endianness bigger".
   bytevector.mo:Expected error in mat bytevector-s16-ref: "bytevector-s16-ref: unrecognized endianness "little"".
   bytevector.mo:Expected error in mat bytevector-s16-ref: "bytevector-s16-ref: unrecognized endianness #t".
@@ -2379,7 +2389,7 @@
   bytevector.mo:Expected error in mat bytevector-u16-ref: "bytevector-u16-ref: #(3 252 5) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-u16-ref: "bytevector-u16-ref: #(3 252 5) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-u16-ref: "bytevector-u16-ref: invalid index -1 for bytevector #vu8(3 252 5)".
---- 2201,2209 ----
+--- 2208,2216 ----
   bytevector.mo:Expected error in mat bytevector-s16-ref: "bytevector-s16-ref: unrecognized endianness bigger".
   bytevector.mo:Expected error in mat bytevector-s16-ref: "bytevector-s16-ref: unrecognized endianness "little"".
   bytevector.mo:Expected error in mat bytevector-s16-ref: "bytevector-s16-ref: unrecognized endianness #t".
@@ -2390,7 +2400,7 @@
   bytevector.mo:Expected error in mat bytevector-u16-ref: "bytevector-u16-ref: #(3 252 5) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-u16-ref: "bytevector-u16-ref: invalid index -1 for bytevector #vu8(3 252 5)".
 ***************
-*** 2213,2222 ****
+*** 2220,2229 ****
   bytevector.mo:Expected error in mat bytevector-u16-ref: "bytevector-u16-ref: unrecognized endianness bigger".
   bytevector.mo:Expected error in mat bytevector-u16-ref: "bytevector-u16-ref: unrecognized endianness "little"".
   bytevector.mo:Expected error in mat bytevector-u16-ref: "bytevector-u16-ref: unrecognized endianness #t".
@@ -2398,10 +2408,10 @@
 ! bytevector.mo:Expected error in mat bytevector-s16-set!: "incorrect argument count in call (bytevector-s16-set! $v1)".
 ! bytevector.mo:Expected error in mat bytevector-s16-set!: "incorrect argument count in call (bytevector-s16-set! $v1 0 0)".
 ! bytevector.mo:Expected error in mat bytevector-s16-set!: "incorrect argument count in call (bytevector-s16-set! $v1 0 0 0 (native-endianness))".
-  bytevector.mo:Expected error in mat bytevector-s16-set!: "bytevector-s16-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-s16-set!: "bytevector-s16-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-s16-set!: "bytevector-s16-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+  bytevector.mo:Expected error in mat bytevector-s16-set!: "bytevector-s16-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-s16-set!: "bytevector-s16-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
---- 2213,2222 ----
+--- 2220,2229 ----
   bytevector.mo:Expected error in mat bytevector-u16-ref: "bytevector-u16-ref: unrecognized endianness bigger".
   bytevector.mo:Expected error in mat bytevector-u16-ref: "bytevector-u16-ref: unrecognized endianness "little"".
   bytevector.mo:Expected error in mat bytevector-u16-ref: "bytevector-u16-ref: unrecognized endianness #t".
@@ -2409,11 +2419,11 @@
 ! bytevector.mo:Expected error in mat bytevector-s16-set!: "incorrect number of arguments to #<procedure bytevector-s16-set!>".
 ! bytevector.mo:Expected error in mat bytevector-s16-set!: "incorrect number of arguments to #<procedure bytevector-s16-set!>".
 ! bytevector.mo:Expected error in mat bytevector-s16-set!: "incorrect number of arguments to #<procedure bytevector-s16-set!>".
-  bytevector.mo:Expected error in mat bytevector-s16-set!: "bytevector-s16-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-s16-set!: "bytevector-s16-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-s16-set!: "bytevector-s16-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+  bytevector.mo:Expected error in mat bytevector-s16-set!: "bytevector-s16-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-s16-set!: "bytevector-s16-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 ***************
-*** 2232,2241 ****
+*** 2239,2248 ****
   bytevector.mo:Expected error in mat bytevector-s16-set!: "bytevector-s16-set!: unrecognized endianness bigger".
   bytevector.mo:Expected error in mat bytevector-s16-set!: "bytevector-s16-set!: unrecognized endianness "little"".
   bytevector.mo:Expected error in mat bytevector-s16-set!: "bytevector-s16-set!: unrecognized endianness #t".
@@ -2421,10 +2431,10 @@
 ! bytevector.mo:Expected error in mat bytevector-u16-set!: "incorrect argument count in call (bytevector-u16-set! $v1)".
 ! bytevector.mo:Expected error in mat bytevector-u16-set!: "incorrect argument count in call (bytevector-u16-set! $v1 0 0)".
 ! bytevector.mo:Expected error in mat bytevector-u16-set!: "incorrect argument count in call (bytevector-u16-set! $v1 0 0 0 (native-endianness))".
-  bytevector.mo:Expected error in mat bytevector-u16-set!: "bytevector-u16-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-u16-set!: "bytevector-u16-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-u16-set!: "bytevector-u16-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+  bytevector.mo:Expected error in mat bytevector-u16-set!: "bytevector-u16-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-u16-set!: "bytevector-u16-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
---- 2232,2241 ----
+--- 2239,2248 ----
   bytevector.mo:Expected error in mat bytevector-s16-set!: "bytevector-s16-set!: unrecognized endianness bigger".
   bytevector.mo:Expected error in mat bytevector-s16-set!: "bytevector-s16-set!: unrecognized endianness "little"".
   bytevector.mo:Expected error in mat bytevector-s16-set!: "bytevector-s16-set!: unrecognized endianness #t".
@@ -2432,11 +2442,11 @@
 ! bytevector.mo:Expected error in mat bytevector-u16-set!: "incorrect number of arguments to #<procedure bytevector-u16-set!>".
 ! bytevector.mo:Expected error in mat bytevector-u16-set!: "incorrect number of arguments to #<procedure bytevector-u16-set!>".
 ! bytevector.mo:Expected error in mat bytevector-u16-set!: "incorrect number of arguments to #<procedure bytevector-u16-set!>".
-  bytevector.mo:Expected error in mat bytevector-u16-set!: "bytevector-u16-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-u16-set!: "bytevector-u16-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-u16-set!: "bytevector-u16-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+  bytevector.mo:Expected error in mat bytevector-u16-set!: "bytevector-u16-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-u16-set!: "bytevector-u16-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 ***************
-*** 2251,2260 ****
+*** 2258,2267 ****
   bytevector.mo:Expected error in mat bytevector-u16-set!: "bytevector-u16-set!: unrecognized endianness bigger".
   bytevector.mo:Expected error in mat bytevector-u16-set!: "bytevector-u16-set!: unrecognized endianness "little"".
   bytevector.mo:Expected error in mat bytevector-u16-set!: "bytevector-u16-set!: unrecognized endianness #t".
@@ -2447,7 +2457,7 @@
   bytevector.mo:Expected error in mat bytevector-s24-ref: "bytevector-s24-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-s24-ref: "bytevector-s24-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-s24-ref: "bytevector-s24-ref: invalid index -1 for bytevector #vu8(3 252 5 0 0 0 ...)".
---- 2251,2260 ----
+--- 2258,2267 ----
   bytevector.mo:Expected error in mat bytevector-u16-set!: "bytevector-u16-set!: unrecognized endianness bigger".
   bytevector.mo:Expected error in mat bytevector-u16-set!: "bytevector-u16-set!: unrecognized endianness "little"".
   bytevector.mo:Expected error in mat bytevector-u16-set!: "bytevector-u16-set!: unrecognized endianness #t".
@@ -2459,7 +2469,7 @@
   bytevector.mo:Expected error in mat bytevector-s24-ref: "bytevector-s24-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-s24-ref: "bytevector-s24-ref: invalid index -1 for bytevector #vu8(3 252 5 0 0 0 ...)".
 ***************
-*** 2264,2273 ****
+*** 2271,2280 ****
   bytevector.mo:Expected error in mat bytevector-s24-ref: "bytevector-s24-ref: unrecognized endianness bigger".
   bytevector.mo:Expected error in mat bytevector-s24-ref: "bytevector-s24-ref: unrecognized endianness "little"".
   bytevector.mo:Expected error in mat bytevector-s24-ref: "bytevector-s24-ref: unrecognized endianness #t".
@@ -2470,7 +2480,7 @@
   bytevector.mo:Expected error in mat bytevector-u24-ref: "bytevector-u24-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-u24-ref: "bytevector-u24-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-u24-ref: "bytevector-u24-ref: invalid index -1 for bytevector #vu8(3 252 5 0 0 0 ...)".
---- 2264,2273 ----
+--- 2271,2280 ----
   bytevector.mo:Expected error in mat bytevector-s24-ref: "bytevector-s24-ref: unrecognized endianness bigger".
   bytevector.mo:Expected error in mat bytevector-s24-ref: "bytevector-s24-ref: unrecognized endianness "little"".
   bytevector.mo:Expected error in mat bytevector-s24-ref: "bytevector-s24-ref: unrecognized endianness #t".
@@ -2482,7 +2492,7 @@
   bytevector.mo:Expected error in mat bytevector-u24-ref: "bytevector-u24-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-u24-ref: "bytevector-u24-ref: invalid index -1 for bytevector #vu8(3 252 5 0 0 0 ...)".
 ***************
-*** 2277,2287 ****
+*** 2284,2294 ****
   bytevector.mo:Expected error in mat bytevector-u24-ref: "bytevector-u24-ref: unrecognized endianness bigger".
   bytevector.mo:Expected error in mat bytevector-u24-ref: "bytevector-u24-ref: unrecognized endianness "little"".
   bytevector.mo:Expected error in mat bytevector-u24-ref: "bytevector-u24-ref: unrecognized endianness #t".
@@ -2491,10 +2501,10 @@
 ! bytevector.mo:Expected error in mat bytevector-s24-set!: "incorrect argument count in call (bytevector-s24-set! $v1 0)".
 ! bytevector.mo:Expected error in mat bytevector-s24-set!: "incorrect argument count in call (bytevector-s24-set! $v1 0 0)".
 ! bytevector.mo:Expected error in mat bytevector-s24-set!: "incorrect argument count in call (bytevector-s24-set! $v1 0 0 (quote big) 0)".
-  bytevector.mo:Expected error in mat bytevector-s24-set!: "bytevector-s24-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-s24-set!: "bytevector-s24-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-s24-set!: "bytevector-s24-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+  bytevector.mo:Expected error in mat bytevector-s24-set!: "bytevector-s24-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-s24-set!: "bytevector-s24-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
---- 2277,2287 ----
+--- 2284,2294 ----
   bytevector.mo:Expected error in mat bytevector-u24-ref: "bytevector-u24-ref: unrecognized endianness bigger".
   bytevector.mo:Expected error in mat bytevector-u24-ref: "bytevector-u24-ref: unrecognized endianness "little"".
   bytevector.mo:Expected error in mat bytevector-u24-ref: "bytevector-u24-ref: unrecognized endianness #t".
@@ -2503,11 +2513,11 @@
 ! bytevector.mo:Expected error in mat bytevector-s24-set!: "incorrect number of arguments to #<procedure bytevector-s24-set!>".
 ! bytevector.mo:Expected error in mat bytevector-s24-set!: "incorrect number of arguments to #<procedure bytevector-s24-set!>".
 ! bytevector.mo:Expected error in mat bytevector-s24-set!: "incorrect number of arguments to #<procedure bytevector-s24-set!>".
-  bytevector.mo:Expected error in mat bytevector-s24-set!: "bytevector-s24-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-s24-set!: "bytevector-s24-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-s24-set!: "bytevector-s24-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+  bytevector.mo:Expected error in mat bytevector-s24-set!: "bytevector-s24-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-s24-set!: "bytevector-s24-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 ***************
-*** 2295,2305 ****
+*** 2302,2312 ****
   bytevector.mo:Expected error in mat bytevector-s24-set!: "bytevector-s24-set!: unrecognized endianness huge".
   bytevector.mo:Expected error in mat bytevector-s24-set!: "bytevector-s24-set!: unrecognized endianness "tiny"".
   bytevector.mo:Expected error in mat bytevector-s24-set!: "bytevector-s24-set!: unrecognized endianness #vu8(173 173 173 173 173 173 ...)".
@@ -2516,10 +2526,10 @@
 ! bytevector.mo:Expected error in mat bytevector-u24-set!: "incorrect argument count in call (bytevector-u24-set! $v1 0)".
 ! bytevector.mo:Expected error in mat bytevector-u24-set!: "incorrect argument count in call (bytevector-u24-set! $v1 0 0)".
 ! bytevector.mo:Expected error in mat bytevector-u24-set!: "incorrect argument count in call (bytevector-u24-set! $v1 0 0 (quote big) 0)".
-  bytevector.mo:Expected error in mat bytevector-u24-set!: "bytevector-u24-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-u24-set!: "bytevector-u24-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-u24-set!: "bytevector-u24-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+  bytevector.mo:Expected error in mat bytevector-u24-set!: "bytevector-u24-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-u24-set!: "bytevector-u24-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
---- 2295,2305 ----
+--- 2302,2312 ----
   bytevector.mo:Expected error in mat bytevector-s24-set!: "bytevector-s24-set!: unrecognized endianness huge".
   bytevector.mo:Expected error in mat bytevector-s24-set!: "bytevector-s24-set!: unrecognized endianness "tiny"".
   bytevector.mo:Expected error in mat bytevector-s24-set!: "bytevector-s24-set!: unrecognized endianness #vu8(173 173 173 173 173 173 ...)".
@@ -2528,11 +2538,11 @@
 ! bytevector.mo:Expected error in mat bytevector-u24-set!: "incorrect number of arguments to #<procedure bytevector-u24-set!>".
 ! bytevector.mo:Expected error in mat bytevector-u24-set!: "incorrect number of arguments to #<procedure bytevector-u24-set!>".
 ! bytevector.mo:Expected error in mat bytevector-u24-set!: "incorrect number of arguments to #<procedure bytevector-u24-set!>".
-  bytevector.mo:Expected error in mat bytevector-u24-set!: "bytevector-u24-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-u24-set!: "bytevector-u24-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-u24-set!: "bytevector-u24-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+  bytevector.mo:Expected error in mat bytevector-u24-set!: "bytevector-u24-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-u24-set!: "bytevector-u24-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 ***************
-*** 2313,2321 ****
+*** 2320,2328 ****
   bytevector.mo:Expected error in mat bytevector-u24-set!: "bytevector-u24-set!: unrecognized endianness huge".
   bytevector.mo:Expected error in mat bytevector-u24-set!: "bytevector-u24-set!: unrecognized endianness "tiny"".
   bytevector.mo:Expected error in mat bytevector-u24-set!: "bytevector-u24-set!: unrecognized endianness #vu8(173 173 173 173 173 173 ...)".
@@ -2542,7 +2552,7 @@
   bytevector.mo:Expected error in mat bytevector-s32-native-ref: "bytevector-s32-native-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-s32-native-ref: "bytevector-s32-native-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-s32-native-ref: "bytevector-s32-native-ref: invalid index -1 for bytevector #vu8(3 252 5 0 0 0 ...)".
---- 2313,2321 ----
+--- 2320,2328 ----
   bytevector.mo:Expected error in mat bytevector-u24-set!: "bytevector-u24-set!: unrecognized endianness huge".
   bytevector.mo:Expected error in mat bytevector-u24-set!: "bytevector-u24-set!: unrecognized endianness "tiny"".
   bytevector.mo:Expected error in mat bytevector-u24-set!: "bytevector-u24-set!: unrecognized endianness #vu8(173 173 173 173 173 173 ...)".
@@ -2553,7 +2563,7 @@
   bytevector.mo:Expected error in mat bytevector-s32-native-ref: "bytevector-s32-native-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-s32-native-ref: "bytevector-s32-native-ref: invalid index -1 for bytevector #vu8(3 252 5 0 0 0 ...)".
 ***************
-*** 2327,2335 ****
+*** 2334,2342 ****
   bytevector.mo:Expected error in mat bytevector-s32-native-ref: "bytevector-s32-native-ref: invalid index 6 for bytevector #vu8(3 252 5 0 0 0 ...)".
   bytevector.mo:Expected error in mat bytevector-s32-native-ref: "bytevector-s32-native-ref: invalid index 7 for bytevector #vu8(3 252 5 0 0 0 ...)".
   bytevector.mo:Expected error in mat bytevector-s32-native-ref: "bytevector-s32-native-ref: invalid index 4.0 for bytevector #vu8(3 252 5 0 0 0 ...)".
@@ -2563,7 +2573,7 @@
   bytevector.mo:Expected error in mat bytevector-u32-native-ref: "bytevector-u32-native-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-u32-native-ref: "bytevector-u32-native-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-u32-native-ref: "bytevector-u32-native-ref: invalid index -1 for bytevector #vu8(3 252 5 0 0 0 ...)".
---- 2327,2335 ----
+--- 2334,2342 ----
   bytevector.mo:Expected error in mat bytevector-s32-native-ref: "bytevector-s32-native-ref: invalid index 6 for bytevector #vu8(3 252 5 0 0 0 ...)".
   bytevector.mo:Expected error in mat bytevector-s32-native-ref: "bytevector-s32-native-ref: invalid index 7 for bytevector #vu8(3 252 5 0 0 0 ...)".
   bytevector.mo:Expected error in mat bytevector-s32-native-ref: "bytevector-s32-native-ref: invalid index 4.0 for bytevector #vu8(3 252 5 0 0 0 ...)".
@@ -2574,7 +2584,7 @@
   bytevector.mo:Expected error in mat bytevector-u32-native-ref: "bytevector-u32-native-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-u32-native-ref: "bytevector-u32-native-ref: invalid index -1 for bytevector #vu8(3 252 5 0 0 0 ...)".
 ***************
-*** 2341,2350 ****
+*** 2348,2357 ****
   bytevector.mo:Expected error in mat bytevector-u32-native-ref: "bytevector-u32-native-ref: invalid index 6 for bytevector #vu8(3 252 5 0 0 0 ...)".
   bytevector.mo:Expected error in mat bytevector-u32-native-ref: "bytevector-u32-native-ref: invalid index 7 for bytevector #vu8(3 252 5 0 0 0 ...)".
   bytevector.mo:Expected error in mat bytevector-u32-native-ref: "bytevector-u32-native-ref: invalid index 4.0 for bytevector #vu8(3 252 5 0 0 0 ...)".
@@ -2582,10 +2592,10 @@
 ! bytevector.mo:Expected error in mat bytevector-s32-native-set!: "incorrect argument count in call (bytevector-s32-native-set! $v1)".
 ! bytevector.mo:Expected error in mat bytevector-s32-native-set!: "incorrect argument count in call (bytevector-s32-native-set! $v1 0)".
 ! bytevector.mo:Expected error in mat bytevector-s32-native-set!: "incorrect argument count in call (bytevector-s32-native-set! $v1 0 0 15)".
-  bytevector.mo:Expected error in mat bytevector-s32-native-set!: "bytevector-s32-native-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-s32-native-set!: "bytevector-s32-native-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-s32-native-set!: "bytevector-s32-native-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+  bytevector.mo:Expected error in mat bytevector-s32-native-set!: "bytevector-s32-native-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-s32-native-set!: "bytevector-s32-native-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
---- 2341,2350 ----
+--- 2348,2357 ----
   bytevector.mo:Expected error in mat bytevector-u32-native-ref: "bytevector-u32-native-ref: invalid index 6 for bytevector #vu8(3 252 5 0 0 0 ...)".
   bytevector.mo:Expected error in mat bytevector-u32-native-ref: "bytevector-u32-native-ref: invalid index 7 for bytevector #vu8(3 252 5 0 0 0 ...)".
   bytevector.mo:Expected error in mat bytevector-u32-native-ref: "bytevector-u32-native-ref: invalid index 4.0 for bytevector #vu8(3 252 5 0 0 0 ...)".
@@ -2593,11 +2603,11 @@
 ! bytevector.mo:Expected error in mat bytevector-s32-native-set!: "incorrect number of arguments to #<procedure bytevector-s32-native-set!>".
 ! bytevector.mo:Expected error in mat bytevector-s32-native-set!: "incorrect number of arguments to #<procedure bytevector-s32-native-set!>".
 ! bytevector.mo:Expected error in mat bytevector-s32-native-set!: "incorrect number of arguments to #<procedure bytevector-s32-native-set!>".
-  bytevector.mo:Expected error in mat bytevector-s32-native-set!: "bytevector-s32-native-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-s32-native-set!: "bytevector-s32-native-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-s32-native-set!: "bytevector-s32-native-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+  bytevector.mo:Expected error in mat bytevector-s32-native-set!: "bytevector-s32-native-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-s32-native-set!: "bytevector-s32-native-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 ***************
-*** 2371,2380 ****
+*** 2378,2387 ****
   bytevector.mo:Expected error in mat bytevector-s32-native-set!: "bytevector-s32-native-set!: invalid value <int>".
   bytevector.mo:Expected error in mat bytevector-s32-native-set!: "bytevector-s32-native-set!: invalid value <-int>".
   bytevector.mo:Expected error in mat bytevector-s32-native-set!: "bytevector-s32-native-set!: invalid value "hello"".
@@ -2605,10 +2615,10 @@
 ! bytevector.mo:Expected error in mat bytevector-u32-native-set!: "incorrect argument count in call (bytevector-u32-native-set! $v1)".
 ! bytevector.mo:Expected error in mat bytevector-u32-native-set!: "incorrect argument count in call (bytevector-u32-native-set! $v1 0)".
 ! bytevector.mo:Expected error in mat bytevector-u32-native-set!: "incorrect argument count in call (bytevector-u32-native-set! $v1 0 0 15)".
-  bytevector.mo:Expected error in mat bytevector-u32-native-set!: "bytevector-u32-native-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-u32-native-set!: "bytevector-u32-native-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-u32-native-set!: "bytevector-u32-native-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+  bytevector.mo:Expected error in mat bytevector-u32-native-set!: "bytevector-u32-native-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-u32-native-set!: "bytevector-u32-native-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
---- 2371,2380 ----
+--- 2378,2387 ----
   bytevector.mo:Expected error in mat bytevector-s32-native-set!: "bytevector-s32-native-set!: invalid value <int>".
   bytevector.mo:Expected error in mat bytevector-s32-native-set!: "bytevector-s32-native-set!: invalid value <-int>".
   bytevector.mo:Expected error in mat bytevector-s32-native-set!: "bytevector-s32-native-set!: invalid value "hello"".
@@ -2616,11 +2626,11 @@
 ! bytevector.mo:Expected error in mat bytevector-u32-native-set!: "incorrect number of arguments to #<procedure bytevector-u32-native-set!>".
 ! bytevector.mo:Expected error in mat bytevector-u32-native-set!: "incorrect number of arguments to #<procedure bytevector-u32-native-set!>".
 ! bytevector.mo:Expected error in mat bytevector-u32-native-set!: "incorrect number of arguments to #<procedure bytevector-u32-native-set!>".
-  bytevector.mo:Expected error in mat bytevector-u32-native-set!: "bytevector-u32-native-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-u32-native-set!: "bytevector-u32-native-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-u32-native-set!: "bytevector-u32-native-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+  bytevector.mo:Expected error in mat bytevector-u32-native-set!: "bytevector-u32-native-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-u32-native-set!: "bytevector-u32-native-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 ***************
-*** 2401,2410 ****
+*** 2408,2417 ****
   bytevector.mo:Expected error in mat bytevector-u32-native-set!: "bytevector-u32-native-set!: invalid value <int>".
   bytevector.mo:Expected error in mat bytevector-u32-native-set!: "bytevector-u32-native-set!: invalid value -1".
   bytevector.mo:Expected error in mat bytevector-u32-native-set!: "bytevector-u32-native-set!: invalid value "hello"".
@@ -2631,7 +2641,7 @@
   bytevector.mo:Expected error in mat bytevector-s32-ref: "bytevector-s32-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-s32-ref: "bytevector-s32-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-s32-ref: "bytevector-s32-ref: invalid index -1 for bytevector #vu8(3 252 5 0 0 0 ...)".
---- 2401,2410 ----
+--- 2408,2417 ----
   bytevector.mo:Expected error in mat bytevector-u32-native-set!: "bytevector-u32-native-set!: invalid value <int>".
   bytevector.mo:Expected error in mat bytevector-u32-native-set!: "bytevector-u32-native-set!: invalid value -1".
   bytevector.mo:Expected error in mat bytevector-u32-native-set!: "bytevector-u32-native-set!: invalid value "hello"".
@@ -2643,7 +2653,7 @@
   bytevector.mo:Expected error in mat bytevector-s32-ref: "bytevector-s32-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-s32-ref: "bytevector-s32-ref: invalid index -1 for bytevector #vu8(3 252 5 0 0 0 ...)".
 ***************
-*** 2414,2423 ****
+*** 2421,2430 ****
   bytevector.mo:Expected error in mat bytevector-s32-ref: "bytevector-s32-ref: unrecognized endianness bigger".
   bytevector.mo:Expected error in mat bytevector-s32-ref: "bytevector-s32-ref: unrecognized endianness "little"".
   bytevector.mo:Expected error in mat bytevector-s32-ref: "bytevector-s32-ref: unrecognized endianness #t".
@@ -2654,7 +2664,7 @@
   bytevector.mo:Expected error in mat bytevector-u32-ref: "bytevector-u32-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-u32-ref: "bytevector-u32-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-u32-ref: "bytevector-u32-ref: invalid index -1 for bytevector #vu8(3 252 5 0 0 0 ...)".
---- 2414,2423 ----
+--- 2421,2430 ----
   bytevector.mo:Expected error in mat bytevector-s32-ref: "bytevector-s32-ref: unrecognized endianness bigger".
   bytevector.mo:Expected error in mat bytevector-s32-ref: "bytevector-s32-ref: unrecognized endianness "little"".
   bytevector.mo:Expected error in mat bytevector-s32-ref: "bytevector-s32-ref: unrecognized endianness #t".
@@ -2666,7 +2676,7 @@
   bytevector.mo:Expected error in mat bytevector-u32-ref: "bytevector-u32-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-u32-ref: "bytevector-u32-ref: invalid index -1 for bytevector #vu8(3 252 5 0 0 0 ...)".
 ***************
-*** 2427,2437 ****
+*** 2434,2444 ****
   bytevector.mo:Expected error in mat bytevector-u32-ref: "bytevector-u32-ref: unrecognized endianness bigger".
   bytevector.mo:Expected error in mat bytevector-u32-ref: "bytevector-u32-ref: unrecognized endianness "little"".
   bytevector.mo:Expected error in mat bytevector-u32-ref: "bytevector-u32-ref: unrecognized endianness #t".
@@ -2675,10 +2685,10 @@
 ! bytevector.mo:Expected error in mat bytevector-s32-set!: "incorrect argument count in call (bytevector-s32-set! $v1 0)".
 ! bytevector.mo:Expected error in mat bytevector-s32-set!: "incorrect argument count in call (bytevector-s32-set! $v1 0 0)".
 ! bytevector.mo:Expected error in mat bytevector-s32-set!: "incorrect argument count in call (bytevector-s32-set! $v1 0 0 (quote big) 0)".
-  bytevector.mo:Expected error in mat bytevector-s32-set!: "bytevector-s32-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-s32-set!: "bytevector-s32-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-s32-set!: "bytevector-s32-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+  bytevector.mo:Expected error in mat bytevector-s32-set!: "bytevector-s32-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-s32-set!: "bytevector-s32-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
---- 2427,2437 ----
+--- 2434,2444 ----
   bytevector.mo:Expected error in mat bytevector-u32-ref: "bytevector-u32-ref: unrecognized endianness bigger".
   bytevector.mo:Expected error in mat bytevector-u32-ref: "bytevector-u32-ref: unrecognized endianness "little"".
   bytevector.mo:Expected error in mat bytevector-u32-ref: "bytevector-u32-ref: unrecognized endianness #t".
@@ -2687,11 +2697,11 @@
 ! bytevector.mo:Expected error in mat bytevector-s32-set!: "incorrect number of arguments to #<procedure bytevector-s32-set!>".
 ! bytevector.mo:Expected error in mat bytevector-s32-set!: "incorrect number of arguments to #<procedure bytevector-s32-set!>".
 ! bytevector.mo:Expected error in mat bytevector-s32-set!: "incorrect number of arguments to #<procedure bytevector-s32-set!>".
-  bytevector.mo:Expected error in mat bytevector-s32-set!: "bytevector-s32-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-s32-set!: "bytevector-s32-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-s32-set!: "bytevector-s32-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+  bytevector.mo:Expected error in mat bytevector-s32-set!: "bytevector-s32-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-s32-set!: "bytevector-s32-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 ***************
-*** 2446,2456 ****
+*** 2453,2463 ****
   bytevector.mo:Expected error in mat bytevector-s32-set!: "bytevector-s32-set!: unrecognized endianness huge".
   bytevector.mo:Expected error in mat bytevector-s32-set!: "bytevector-s32-set!: unrecognized endianness "tiny"".
   bytevector.mo:Expected error in mat bytevector-s32-set!: "bytevector-s32-set!: unrecognized endianness #vu8(173 173 173 173 173 173 ...)".
@@ -2700,10 +2710,10 @@
 ! bytevector.mo:Expected error in mat bytevector-u32-set!: "incorrect argument count in call (bytevector-u32-set! $v1 0)".
 ! bytevector.mo:Expected error in mat bytevector-u32-set!: "incorrect argument count in call (bytevector-u32-set! $v1 0 0)".
 ! bytevector.mo:Expected error in mat bytevector-u32-set!: "incorrect argument count in call (bytevector-u32-set! $v1 0 0 (quote big) 0)".
-  bytevector.mo:Expected error in mat bytevector-u32-set!: "bytevector-u32-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-u32-set!: "bytevector-u32-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-u32-set!: "bytevector-u32-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+  bytevector.mo:Expected error in mat bytevector-u32-set!: "bytevector-u32-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-u32-set!: "bytevector-u32-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
---- 2446,2456 ----
+--- 2453,2463 ----
   bytevector.mo:Expected error in mat bytevector-s32-set!: "bytevector-s32-set!: unrecognized endianness huge".
   bytevector.mo:Expected error in mat bytevector-s32-set!: "bytevector-s32-set!: unrecognized endianness "tiny"".
   bytevector.mo:Expected error in mat bytevector-s32-set!: "bytevector-s32-set!: unrecognized endianness #vu8(173 173 173 173 173 173 ...)".
@@ -2712,11 +2722,11 @@
 ! bytevector.mo:Expected error in mat bytevector-u32-set!: "incorrect number of arguments to #<procedure bytevector-u32-set!>".
 ! bytevector.mo:Expected error in mat bytevector-u32-set!: "incorrect number of arguments to #<procedure bytevector-u32-set!>".
 ! bytevector.mo:Expected error in mat bytevector-u32-set!: "incorrect number of arguments to #<procedure bytevector-u32-set!>".
-  bytevector.mo:Expected error in mat bytevector-u32-set!: "bytevector-u32-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-u32-set!: "bytevector-u32-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-u32-set!: "bytevector-u32-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+  bytevector.mo:Expected error in mat bytevector-u32-set!: "bytevector-u32-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-u32-set!: "bytevector-u32-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 ***************
-*** 2465,2474 ****
+*** 2472,2481 ****
   bytevector.mo:Expected error in mat bytevector-u32-set!: "bytevector-u32-set!: unrecognized endianness huge".
   bytevector.mo:Expected error in mat bytevector-u32-set!: "bytevector-u32-set!: unrecognized endianness "tiny"".
   bytevector.mo:Expected error in mat bytevector-u32-set!: "bytevector-u32-set!: unrecognized endianness #vu8(173 173 173 173 173 173 ...)".
@@ -2727,7 +2737,7 @@
   bytevector.mo:Expected error in mat bytevector-s40-ref: "bytevector-s40-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-s40-ref: "bytevector-s40-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-s40-ref: "bytevector-s40-ref: invalid index -1 for bytevector #vu8(3 252 5 0 0 0 ...)".
---- 2465,2474 ----
+--- 2472,2481 ----
   bytevector.mo:Expected error in mat bytevector-u32-set!: "bytevector-u32-set!: unrecognized endianness huge".
   bytevector.mo:Expected error in mat bytevector-u32-set!: "bytevector-u32-set!: unrecognized endianness "tiny"".
   bytevector.mo:Expected error in mat bytevector-u32-set!: "bytevector-u32-set!: unrecognized endianness #vu8(173 173 173 173 173 173 ...)".
@@ -2739,7 +2749,7 @@
   bytevector.mo:Expected error in mat bytevector-s40-ref: "bytevector-s40-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-s40-ref: "bytevector-s40-ref: invalid index -1 for bytevector #vu8(3 252 5 0 0 0 ...)".
 ***************
-*** 2478,2487 ****
+*** 2485,2494 ****
   bytevector.mo:Expected error in mat bytevector-s40-ref: "bytevector-s40-ref: unrecognized endianness bigger".
   bytevector.mo:Expected error in mat bytevector-s40-ref: "bytevector-s40-ref: unrecognized endianness "little"".
   bytevector.mo:Expected error in mat bytevector-s40-ref: "bytevector-s40-ref: unrecognized endianness #t".
@@ -2750,7 +2760,7 @@
   bytevector.mo:Expected error in mat bytevector-u40-ref: "bytevector-u40-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-u40-ref: "bytevector-u40-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-u40-ref: "bytevector-u40-ref: invalid index -1 for bytevector #vu8(3 252 5 0 0 0 ...)".
---- 2478,2487 ----
+--- 2485,2494 ----
   bytevector.mo:Expected error in mat bytevector-s40-ref: "bytevector-s40-ref: unrecognized endianness bigger".
   bytevector.mo:Expected error in mat bytevector-s40-ref: "bytevector-s40-ref: unrecognized endianness "little"".
   bytevector.mo:Expected error in mat bytevector-s40-ref: "bytevector-s40-ref: unrecognized endianness #t".
@@ -2762,7 +2772,7 @@
   bytevector.mo:Expected error in mat bytevector-u40-ref: "bytevector-u40-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-u40-ref: "bytevector-u40-ref: invalid index -1 for bytevector #vu8(3 252 5 0 0 0 ...)".
 ***************
-*** 2491,2501 ****
+*** 2498,2508 ****
   bytevector.mo:Expected error in mat bytevector-u40-ref: "bytevector-u40-ref: unrecognized endianness bigger".
   bytevector.mo:Expected error in mat bytevector-u40-ref: "bytevector-u40-ref: unrecognized endianness "little"".
   bytevector.mo:Expected error in mat bytevector-u40-ref: "bytevector-u40-ref: unrecognized endianness #t".
@@ -2771,10 +2781,10 @@
 ! bytevector.mo:Expected error in mat bytevector-s40-set!: "incorrect argument count in call (bytevector-s40-set! $v1 0)".
 ! bytevector.mo:Expected error in mat bytevector-s40-set!: "incorrect argument count in call (bytevector-s40-set! $v1 0 0)".
 ! bytevector.mo:Expected error in mat bytevector-s40-set!: "incorrect argument count in call (bytevector-s40-set! $v1 0 0 (quote big) 0)".
-  bytevector.mo:Expected error in mat bytevector-s40-set!: "bytevector-s40-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-s40-set!: "bytevector-s40-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-s40-set!: "bytevector-s40-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+  bytevector.mo:Expected error in mat bytevector-s40-set!: "bytevector-s40-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-s40-set!: "bytevector-s40-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
---- 2491,2501 ----
+--- 2498,2508 ----
   bytevector.mo:Expected error in mat bytevector-u40-ref: "bytevector-u40-ref: unrecognized endianness bigger".
   bytevector.mo:Expected error in mat bytevector-u40-ref: "bytevector-u40-ref: unrecognized endianness "little"".
   bytevector.mo:Expected error in mat bytevector-u40-ref: "bytevector-u40-ref: unrecognized endianness #t".
@@ -2783,11 +2793,11 @@
 ! bytevector.mo:Expected error in mat bytevector-s40-set!: "incorrect number of arguments to #<procedure bytevector-s40-set!>".
 ! bytevector.mo:Expected error in mat bytevector-s40-set!: "incorrect number of arguments to #<procedure bytevector-s40-set!>".
 ! bytevector.mo:Expected error in mat bytevector-s40-set!: "incorrect number of arguments to #<procedure bytevector-s40-set!>".
-  bytevector.mo:Expected error in mat bytevector-s40-set!: "bytevector-s40-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-s40-set!: "bytevector-s40-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-s40-set!: "bytevector-s40-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+  bytevector.mo:Expected error in mat bytevector-s40-set!: "bytevector-s40-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-s40-set!: "bytevector-s40-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 ***************
-*** 2509,2519 ****
+*** 2516,2526 ****
   bytevector.mo:Expected error in mat bytevector-s40-set!: "bytevector-s40-set!: unrecognized endianness huge".
   bytevector.mo:Expected error in mat bytevector-s40-set!: "bytevector-s40-set!: unrecognized endianness "tiny"".
   bytevector.mo:Expected error in mat bytevector-s40-set!: "bytevector-s40-set!: unrecognized endianness #vu8(173 173 173 173 173 173 ...)".
@@ -2796,10 +2806,10 @@
 ! bytevector.mo:Expected error in mat bytevector-u40-set!: "incorrect argument count in call (bytevector-u40-set! $v1 0)".
 ! bytevector.mo:Expected error in mat bytevector-u40-set!: "incorrect argument count in call (bytevector-u40-set! $v1 0 0)".
 ! bytevector.mo:Expected error in mat bytevector-u40-set!: "incorrect argument count in call (bytevector-u40-set! $v1 0 0 (quote big) 0)".
-  bytevector.mo:Expected error in mat bytevector-u40-set!: "bytevector-u40-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-u40-set!: "bytevector-u40-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-u40-set!: "bytevector-u40-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+  bytevector.mo:Expected error in mat bytevector-u40-set!: "bytevector-u40-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-u40-set!: "bytevector-u40-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
---- 2509,2519 ----
+--- 2516,2526 ----
   bytevector.mo:Expected error in mat bytevector-s40-set!: "bytevector-s40-set!: unrecognized endianness huge".
   bytevector.mo:Expected error in mat bytevector-s40-set!: "bytevector-s40-set!: unrecognized endianness "tiny"".
   bytevector.mo:Expected error in mat bytevector-s40-set!: "bytevector-s40-set!: unrecognized endianness #vu8(173 173 173 173 173 173 ...)".
@@ -2808,11 +2818,11 @@
 ! bytevector.mo:Expected error in mat bytevector-u40-set!: "incorrect number of arguments to #<procedure bytevector-u40-set!>".
 ! bytevector.mo:Expected error in mat bytevector-u40-set!: "incorrect number of arguments to #<procedure bytevector-u40-set!>".
 ! bytevector.mo:Expected error in mat bytevector-u40-set!: "incorrect number of arguments to #<procedure bytevector-u40-set!>".
-  bytevector.mo:Expected error in mat bytevector-u40-set!: "bytevector-u40-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-u40-set!: "bytevector-u40-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-u40-set!: "bytevector-u40-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+  bytevector.mo:Expected error in mat bytevector-u40-set!: "bytevector-u40-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-u40-set!: "bytevector-u40-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 ***************
-*** 2527,2536 ****
+*** 2534,2543 ****
   bytevector.mo:Expected error in mat bytevector-u40-set!: "bytevector-u40-set!: unrecognized endianness huge".
   bytevector.mo:Expected error in mat bytevector-u40-set!: "bytevector-u40-set!: unrecognized endianness "tiny"".
   bytevector.mo:Expected error in mat bytevector-u40-set!: "bytevector-u40-set!: unrecognized endianness #vu8(173 173 173 173 173 173 ...)".
@@ -2823,7 +2833,7 @@
   bytevector.mo:Expected error in mat bytevector-s48-ref: "bytevector-s48-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-s48-ref: "bytevector-s48-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-s48-ref: "bytevector-s48-ref: invalid index -1 for bytevector #vu8(3 252 5 0 0 0 ...)".
---- 2527,2536 ----
+--- 2534,2543 ----
   bytevector.mo:Expected error in mat bytevector-u40-set!: "bytevector-u40-set!: unrecognized endianness huge".
   bytevector.mo:Expected error in mat bytevector-u40-set!: "bytevector-u40-set!: unrecognized endianness "tiny"".
   bytevector.mo:Expected error in mat bytevector-u40-set!: "bytevector-u40-set!: unrecognized endianness #vu8(173 173 173 173 173 173 ...)".
@@ -2835,7 +2845,7 @@
   bytevector.mo:Expected error in mat bytevector-s48-ref: "bytevector-s48-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-s48-ref: "bytevector-s48-ref: invalid index -1 for bytevector #vu8(3 252 5 0 0 0 ...)".
 ***************
-*** 2540,2549 ****
+*** 2547,2556 ****
   bytevector.mo:Expected error in mat bytevector-s48-ref: "bytevector-s48-ref: unrecognized endianness bigger".
   bytevector.mo:Expected error in mat bytevector-s48-ref: "bytevector-s48-ref: unrecognized endianness "little"".
   bytevector.mo:Expected error in mat bytevector-s48-ref: "bytevector-s48-ref: unrecognized endianness #t".
@@ -2846,7 +2856,7 @@
   bytevector.mo:Expected error in mat bytevector-u48-ref: "bytevector-u48-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-u48-ref: "bytevector-u48-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-u48-ref: "bytevector-u48-ref: invalid index -1 for bytevector #vu8(3 252 5 0 0 0 ...)".
---- 2540,2549 ----
+--- 2547,2556 ----
   bytevector.mo:Expected error in mat bytevector-s48-ref: "bytevector-s48-ref: unrecognized endianness bigger".
   bytevector.mo:Expected error in mat bytevector-s48-ref: "bytevector-s48-ref: unrecognized endianness "little"".
   bytevector.mo:Expected error in mat bytevector-s48-ref: "bytevector-s48-ref: unrecognized endianness #t".
@@ -2858,7 +2868,7 @@
   bytevector.mo:Expected error in mat bytevector-u48-ref: "bytevector-u48-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-u48-ref: "bytevector-u48-ref: invalid index -1 for bytevector #vu8(3 252 5 0 0 0 ...)".
 ***************
-*** 2553,2563 ****
+*** 2560,2570 ****
   bytevector.mo:Expected error in mat bytevector-u48-ref: "bytevector-u48-ref: unrecognized endianness bigger".
   bytevector.mo:Expected error in mat bytevector-u48-ref: "bytevector-u48-ref: unrecognized endianness "little"".
   bytevector.mo:Expected error in mat bytevector-u48-ref: "bytevector-u48-ref: unrecognized endianness #t".
@@ -2867,10 +2877,10 @@
 ! bytevector.mo:Expected error in mat bytevector-s48-set!: "incorrect argument count in call (bytevector-s48-set! $v1 0)".
 ! bytevector.mo:Expected error in mat bytevector-s48-set!: "incorrect argument count in call (bytevector-s48-set! $v1 0 0)".
 ! bytevector.mo:Expected error in mat bytevector-s48-set!: "incorrect argument count in call (bytevector-s48-set! $v1 0 0 (quote big) 0)".
-  bytevector.mo:Expected error in mat bytevector-s48-set!: "bytevector-s48-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-s48-set!: "bytevector-s48-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-s48-set!: "bytevector-s48-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+  bytevector.mo:Expected error in mat bytevector-s48-set!: "bytevector-s48-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-s48-set!: "bytevector-s48-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
---- 2553,2563 ----
+--- 2560,2570 ----
   bytevector.mo:Expected error in mat bytevector-u48-ref: "bytevector-u48-ref: unrecognized endianness bigger".
   bytevector.mo:Expected error in mat bytevector-u48-ref: "bytevector-u48-ref: unrecognized endianness "little"".
   bytevector.mo:Expected error in mat bytevector-u48-ref: "bytevector-u48-ref: unrecognized endianness #t".
@@ -2879,11 +2889,11 @@
 ! bytevector.mo:Expected error in mat bytevector-s48-set!: "incorrect number of arguments to #<procedure bytevector-s48-set!>".
 ! bytevector.mo:Expected error in mat bytevector-s48-set!: "incorrect number of arguments to #<procedure bytevector-s48-set!>".
 ! bytevector.mo:Expected error in mat bytevector-s48-set!: "incorrect number of arguments to #<procedure bytevector-s48-set!>".
-  bytevector.mo:Expected error in mat bytevector-s48-set!: "bytevector-s48-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-s48-set!: "bytevector-s48-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-s48-set!: "bytevector-s48-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+  bytevector.mo:Expected error in mat bytevector-s48-set!: "bytevector-s48-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-s48-set!: "bytevector-s48-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 ***************
-*** 2571,2581 ****
+*** 2578,2588 ****
   bytevector.mo:Expected error in mat bytevector-s48-set!: "bytevector-s48-set!: unrecognized endianness huge".
   bytevector.mo:Expected error in mat bytevector-s48-set!: "bytevector-s48-set!: unrecognized endianness "tiny"".
   bytevector.mo:Expected error in mat bytevector-s48-set!: "bytevector-s48-set!: unrecognized endianness #vu8(173 173 173 173 173 173 ...)".
@@ -2892,10 +2902,10 @@
 ! bytevector.mo:Expected error in mat bytevector-u48-set!: "incorrect argument count in call (bytevector-u48-set! $v1 0)".
 ! bytevector.mo:Expected error in mat bytevector-u48-set!: "incorrect argument count in call (bytevector-u48-set! $v1 0 0)".
 ! bytevector.mo:Expected error in mat bytevector-u48-set!: "incorrect argument count in call (bytevector-u48-set! $v1 0 0 (quote big) 0)".
-  bytevector.mo:Expected error in mat bytevector-u48-set!: "bytevector-u48-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-u48-set!: "bytevector-u48-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-u48-set!: "bytevector-u48-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+  bytevector.mo:Expected error in mat bytevector-u48-set!: "bytevector-u48-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-u48-set!: "bytevector-u48-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
---- 2571,2581 ----
+--- 2578,2588 ----
   bytevector.mo:Expected error in mat bytevector-s48-set!: "bytevector-s48-set!: unrecognized endianness huge".
   bytevector.mo:Expected error in mat bytevector-s48-set!: "bytevector-s48-set!: unrecognized endianness "tiny"".
   bytevector.mo:Expected error in mat bytevector-s48-set!: "bytevector-s48-set!: unrecognized endianness #vu8(173 173 173 173 173 173 ...)".
@@ -2904,11 +2914,11 @@
 ! bytevector.mo:Expected error in mat bytevector-u48-set!: "incorrect number of arguments to #<procedure bytevector-u48-set!>".
 ! bytevector.mo:Expected error in mat bytevector-u48-set!: "incorrect number of arguments to #<procedure bytevector-u48-set!>".
 ! bytevector.mo:Expected error in mat bytevector-u48-set!: "incorrect number of arguments to #<procedure bytevector-u48-set!>".
-  bytevector.mo:Expected error in mat bytevector-u48-set!: "bytevector-u48-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-u48-set!: "bytevector-u48-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-u48-set!: "bytevector-u48-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+  bytevector.mo:Expected error in mat bytevector-u48-set!: "bytevector-u48-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-u48-set!: "bytevector-u48-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 ***************
-*** 2589,2598 ****
+*** 2596,2605 ****
   bytevector.mo:Expected error in mat bytevector-u48-set!: "bytevector-u48-set!: unrecognized endianness huge".
   bytevector.mo:Expected error in mat bytevector-u48-set!: "bytevector-u48-set!: unrecognized endianness "tiny"".
   bytevector.mo:Expected error in mat bytevector-u48-set!: "bytevector-u48-set!: unrecognized endianness #vu8(173 173 173 173 173 173 ...)".
@@ -2919,7 +2929,7 @@
   bytevector.mo:Expected error in mat bytevector-s56-ref: "bytevector-s56-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-s56-ref: "bytevector-s56-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-s56-ref: "bytevector-s56-ref: invalid index -1 for bytevector #vu8(3 252 5 0 0 0 ...)".
---- 2589,2598 ----
+--- 2596,2605 ----
   bytevector.mo:Expected error in mat bytevector-u48-set!: "bytevector-u48-set!: unrecognized endianness huge".
   bytevector.mo:Expected error in mat bytevector-u48-set!: "bytevector-u48-set!: unrecognized endianness "tiny"".
   bytevector.mo:Expected error in mat bytevector-u48-set!: "bytevector-u48-set!: unrecognized endianness #vu8(173 173 173 173 173 173 ...)".
@@ -2931,7 +2941,7 @@
   bytevector.mo:Expected error in mat bytevector-s56-ref: "bytevector-s56-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-s56-ref: "bytevector-s56-ref: invalid index -1 for bytevector #vu8(3 252 5 0 0 0 ...)".
 ***************
-*** 2602,2611 ****
+*** 2609,2618 ****
   bytevector.mo:Expected error in mat bytevector-s56-ref: "bytevector-s56-ref: unrecognized endianness bigger".
   bytevector.mo:Expected error in mat bytevector-s56-ref: "bytevector-s56-ref: unrecognized endianness "little"".
   bytevector.mo:Expected error in mat bytevector-s56-ref: "bytevector-s56-ref: unrecognized endianness #t".
@@ -2942,7 +2952,7 @@
   bytevector.mo:Expected error in mat bytevector-u56-ref: "bytevector-u56-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-u56-ref: "bytevector-u56-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-u56-ref: "bytevector-u56-ref: invalid index -1 for bytevector #vu8(3 252 5 0 0 0 ...)".
---- 2602,2611 ----
+--- 2609,2618 ----
   bytevector.mo:Expected error in mat bytevector-s56-ref: "bytevector-s56-ref: unrecognized endianness bigger".
   bytevector.mo:Expected error in mat bytevector-s56-ref: "bytevector-s56-ref: unrecognized endianness "little"".
   bytevector.mo:Expected error in mat bytevector-s56-ref: "bytevector-s56-ref: unrecognized endianness #t".
@@ -2954,7 +2964,7 @@
   bytevector.mo:Expected error in mat bytevector-u56-ref: "bytevector-u56-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-u56-ref: "bytevector-u56-ref: invalid index -1 for bytevector #vu8(3 252 5 0 0 0 ...)".
 ***************
-*** 2615,2625 ****
+*** 2622,2632 ****
   bytevector.mo:Expected error in mat bytevector-u56-ref: "bytevector-u56-ref: unrecognized endianness bigger".
   bytevector.mo:Expected error in mat bytevector-u56-ref: "bytevector-u56-ref: unrecognized endianness "little"".
   bytevector.mo:Expected error in mat bytevector-u56-ref: "bytevector-u56-ref: unrecognized endianness #t".
@@ -2963,10 +2973,10 @@
 ! bytevector.mo:Expected error in mat bytevector-s56-set!: "incorrect argument count in call (bytevector-s56-set! $v1 0)".
 ! bytevector.mo:Expected error in mat bytevector-s56-set!: "incorrect argument count in call (bytevector-s56-set! $v1 0 0)".
 ! bytevector.mo:Expected error in mat bytevector-s56-set!: "incorrect argument count in call (bytevector-s56-set! $v1 0 0 (quote big) 0)".
-  bytevector.mo:Expected error in mat bytevector-s56-set!: "bytevector-s56-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-s56-set!: "bytevector-s56-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-s56-set!: "bytevector-s56-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+  bytevector.mo:Expected error in mat bytevector-s56-set!: "bytevector-s56-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-s56-set!: "bytevector-s56-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
---- 2615,2625 ----
+--- 2622,2632 ----
   bytevector.mo:Expected error in mat bytevector-u56-ref: "bytevector-u56-ref: unrecognized endianness bigger".
   bytevector.mo:Expected error in mat bytevector-u56-ref: "bytevector-u56-ref: unrecognized endianness "little"".
   bytevector.mo:Expected error in mat bytevector-u56-ref: "bytevector-u56-ref: unrecognized endianness #t".
@@ -2975,11 +2985,11 @@
 ! bytevector.mo:Expected error in mat bytevector-s56-set!: "incorrect number of arguments to #<procedure bytevector-s56-set!>".
 ! bytevector.mo:Expected error in mat bytevector-s56-set!: "incorrect number of arguments to #<procedure bytevector-s56-set!>".
 ! bytevector.mo:Expected error in mat bytevector-s56-set!: "incorrect number of arguments to #<procedure bytevector-s56-set!>".
-  bytevector.mo:Expected error in mat bytevector-s56-set!: "bytevector-s56-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-s56-set!: "bytevector-s56-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-s56-set!: "bytevector-s56-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+  bytevector.mo:Expected error in mat bytevector-s56-set!: "bytevector-s56-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-s56-set!: "bytevector-s56-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 ***************
-*** 2633,2643 ****
+*** 2640,2650 ****
   bytevector.mo:Expected error in mat bytevector-s56-set!: "bytevector-s56-set!: unrecognized endianness huge".
   bytevector.mo:Expected error in mat bytevector-s56-set!: "bytevector-s56-set!: unrecognized endianness "tiny"".
   bytevector.mo:Expected error in mat bytevector-s56-set!: "bytevector-s56-set!: unrecognized endianness #vu8(173 173 173 173 173 173 ...)".
@@ -2988,10 +2998,10 @@
 ! bytevector.mo:Expected error in mat bytevector-u56-set!: "incorrect argument count in call (bytevector-u56-set! $v1 0)".
 ! bytevector.mo:Expected error in mat bytevector-u56-set!: "incorrect argument count in call (bytevector-u56-set! $v1 0 0)".
 ! bytevector.mo:Expected error in mat bytevector-u56-set!: "incorrect argument count in call (bytevector-u56-set! $v1 0 0 (quote big) 0)".
-  bytevector.mo:Expected error in mat bytevector-u56-set!: "bytevector-u56-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-u56-set!: "bytevector-u56-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-u56-set!: "bytevector-u56-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+  bytevector.mo:Expected error in mat bytevector-u56-set!: "bytevector-u56-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-u56-set!: "bytevector-u56-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
---- 2633,2643 ----
+--- 2640,2650 ----
   bytevector.mo:Expected error in mat bytevector-s56-set!: "bytevector-s56-set!: unrecognized endianness huge".
   bytevector.mo:Expected error in mat bytevector-s56-set!: "bytevector-s56-set!: unrecognized endianness "tiny"".
   bytevector.mo:Expected error in mat bytevector-s56-set!: "bytevector-s56-set!: unrecognized endianness #vu8(173 173 173 173 173 173 ...)".
@@ -3000,11 +3010,11 @@
 ! bytevector.mo:Expected error in mat bytevector-u56-set!: "incorrect number of arguments to #<procedure bytevector-u56-set!>".
 ! bytevector.mo:Expected error in mat bytevector-u56-set!: "incorrect number of arguments to #<procedure bytevector-u56-set!>".
 ! bytevector.mo:Expected error in mat bytevector-u56-set!: "incorrect number of arguments to #<procedure bytevector-u56-set!>".
-  bytevector.mo:Expected error in mat bytevector-u56-set!: "bytevector-u56-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-u56-set!: "bytevector-u56-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-u56-set!: "bytevector-u56-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+  bytevector.mo:Expected error in mat bytevector-u56-set!: "bytevector-u56-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-u56-set!: "bytevector-u56-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 ***************
-*** 2651,2659 ****
+*** 2658,2666 ****
   bytevector.mo:Expected error in mat bytevector-u56-set!: "bytevector-u56-set!: unrecognized endianness huge".
   bytevector.mo:Expected error in mat bytevector-u56-set!: "bytevector-u56-set!: unrecognized endianness "tiny"".
   bytevector.mo:Expected error in mat bytevector-u56-set!: "bytevector-u56-set!: unrecognized endianness #vu8(173 173 173 173 173 173 ...)".
@@ -3014,7 +3024,7 @@
   bytevector.mo:Expected error in mat bytevector-s64-native-ref: "bytevector-s64-native-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-s64-native-ref: "bytevector-s64-native-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-s64-native-ref: "bytevector-s64-native-ref: invalid index -1 for bytevector #vu8(0 0 0 0 0 0 ...)".
---- 2651,2659 ----
+--- 2658,2666 ----
   bytevector.mo:Expected error in mat bytevector-u56-set!: "bytevector-u56-set!: unrecognized endianness huge".
   bytevector.mo:Expected error in mat bytevector-u56-set!: "bytevector-u56-set!: unrecognized endianness "tiny"".
   bytevector.mo:Expected error in mat bytevector-u56-set!: "bytevector-u56-set!: unrecognized endianness #vu8(173 173 173 173 173 173 ...)".
@@ -3025,7 +3035,7 @@
   bytevector.mo:Expected error in mat bytevector-s64-native-ref: "bytevector-s64-native-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-s64-native-ref: "bytevector-s64-native-ref: invalid index -1 for bytevector #vu8(0 0 0 0 0 0 ...)".
 ***************
-*** 2683,2691 ****
+*** 2690,2698 ****
   bytevector.mo:Expected error in mat bytevector-s64-native-ref: "bytevector-s64-native-ref: invalid index 102 for bytevector #vu8(0 0 0 0 0 0 ...)".
   bytevector.mo:Expected error in mat bytevector-s64-native-ref: "bytevector-s64-native-ref: invalid index 103 for bytevector #vu8(0 0 0 0 0 0 ...)".
   bytevector.mo:Expected error in mat bytevector-s64-native-ref: "bytevector-s64-native-ref: invalid index 4.0 for bytevector #vu8(0 0 0 0 0 0 ...)".
@@ -3035,7 +3045,7 @@
   bytevector.mo:Expected error in mat bytevector-u64-native-ref: "bytevector-u64-native-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-u64-native-ref: "bytevector-u64-native-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-u64-native-ref: "bytevector-u64-native-ref: invalid index -1 for bytevector #vu8(0 0 0 0 0 0 ...)".
---- 2683,2691 ----
+--- 2690,2698 ----
   bytevector.mo:Expected error in mat bytevector-s64-native-ref: "bytevector-s64-native-ref: invalid index 102 for bytevector #vu8(0 0 0 0 0 0 ...)".
   bytevector.mo:Expected error in mat bytevector-s64-native-ref: "bytevector-s64-native-ref: invalid index 103 for bytevector #vu8(0 0 0 0 0 0 ...)".
   bytevector.mo:Expected error in mat bytevector-s64-native-ref: "bytevector-s64-native-ref: invalid index 4.0 for bytevector #vu8(0 0 0 0 0 0 ...)".
@@ -3046,7 +3056,7 @@
   bytevector.mo:Expected error in mat bytevector-u64-native-ref: "bytevector-u64-native-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-u64-native-ref: "bytevector-u64-native-ref: invalid index -1 for bytevector #vu8(0 0 0 0 0 0 ...)".
 ***************
-*** 2715,2724 ****
+*** 2722,2731 ****
   bytevector.mo:Expected error in mat bytevector-u64-native-ref: "bytevector-u64-native-ref: invalid index 102 for bytevector #vu8(0 0 0 0 0 0 ...)".
   bytevector.mo:Expected error in mat bytevector-u64-native-ref: "bytevector-u64-native-ref: invalid index 103 for bytevector #vu8(0 0 0 0 0 0 ...)".
   bytevector.mo:Expected error in mat bytevector-u64-native-ref: "bytevector-u64-native-ref: invalid index 4.0 for bytevector #vu8(0 0 0 0 0 0 ...)".
@@ -3054,10 +3064,10 @@
 ! bytevector.mo:Expected error in mat bytevector-s64-native-set!: "incorrect argument count in call (bytevector-s64-native-set! $v1)".
 ! bytevector.mo:Expected error in mat bytevector-s64-native-set!: "incorrect argument count in call (bytevector-s64-native-set! $v1 0)".
 ! bytevector.mo:Expected error in mat bytevector-s64-native-set!: "incorrect argument count in call (bytevector-s64-native-set! $v1 0 0 15)".
-  bytevector.mo:Expected error in mat bytevector-s64-native-set!: "bytevector-s64-native-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-s64-native-set!: "bytevector-s64-native-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-s64-native-set!: "bytevector-s64-native-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+  bytevector.mo:Expected error in mat bytevector-s64-native-set!: "bytevector-s64-native-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-s64-native-set!: "bytevector-s64-native-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
---- 2715,2724 ----
+--- 2722,2731 ----
   bytevector.mo:Expected error in mat bytevector-u64-native-ref: "bytevector-u64-native-ref: invalid index 102 for bytevector #vu8(0 0 0 0 0 0 ...)".
   bytevector.mo:Expected error in mat bytevector-u64-native-ref: "bytevector-u64-native-ref: invalid index 103 for bytevector #vu8(0 0 0 0 0 0 ...)".
   bytevector.mo:Expected error in mat bytevector-u64-native-ref: "bytevector-u64-native-ref: invalid index 4.0 for bytevector #vu8(0 0 0 0 0 0 ...)".
@@ -3065,11 +3075,11 @@
 ! bytevector.mo:Expected error in mat bytevector-s64-native-set!: "incorrect number of arguments to #<procedure bytevector-s64-native-set!>".
 ! bytevector.mo:Expected error in mat bytevector-s64-native-set!: "incorrect number of arguments to #<procedure bytevector-s64-native-set!>".
 ! bytevector.mo:Expected error in mat bytevector-s64-native-set!: "incorrect number of arguments to #<procedure bytevector-s64-native-set!>".
-  bytevector.mo:Expected error in mat bytevector-s64-native-set!: "bytevector-s64-native-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-s64-native-set!: "bytevector-s64-native-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-s64-native-set!: "bytevector-s64-native-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+  bytevector.mo:Expected error in mat bytevector-s64-native-set!: "bytevector-s64-native-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-s64-native-set!: "bytevector-s64-native-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 ***************
-*** 2752,2761 ****
+*** 2759,2768 ****
   bytevector.mo:Expected error in mat bytevector-s64-native-set!: "bytevector-s64-native-set!: invalid value <int>".
   bytevector.mo:Expected error in mat bytevector-s64-native-set!: "bytevector-s64-native-set!: invalid value <-int>".
   bytevector.mo:Expected error in mat bytevector-s64-native-set!: "bytevector-s64-native-set!: invalid value "hello"".
@@ -3077,10 +3087,10 @@
 ! bytevector.mo:Expected error in mat bytevector-u64-native-set!: "incorrect argument count in call (bytevector-u64-native-set! $v1)".
 ! bytevector.mo:Expected error in mat bytevector-u64-native-set!: "incorrect argument count in call (bytevector-u64-native-set! $v1 0)".
 ! bytevector.mo:Expected error in mat bytevector-u64-native-set!: "incorrect argument count in call (bytevector-u64-native-set! $v1 0 0 15)".
-  bytevector.mo:Expected error in mat bytevector-u64-native-set!: "bytevector-u64-native-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-u64-native-set!: "bytevector-u64-native-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-u64-native-set!: "bytevector-u64-native-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+  bytevector.mo:Expected error in mat bytevector-u64-native-set!: "bytevector-u64-native-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-u64-native-set!: "bytevector-u64-native-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
---- 2752,2761 ----
+--- 2759,2768 ----
   bytevector.mo:Expected error in mat bytevector-s64-native-set!: "bytevector-s64-native-set!: invalid value <int>".
   bytevector.mo:Expected error in mat bytevector-s64-native-set!: "bytevector-s64-native-set!: invalid value <-int>".
   bytevector.mo:Expected error in mat bytevector-s64-native-set!: "bytevector-s64-native-set!: invalid value "hello"".
@@ -3088,11 +3098,11 @@
 ! bytevector.mo:Expected error in mat bytevector-u64-native-set!: "incorrect number of arguments to #<procedure bytevector-u64-native-set!>".
 ! bytevector.mo:Expected error in mat bytevector-u64-native-set!: "incorrect number of arguments to #<procedure bytevector-u64-native-set!>".
 ! bytevector.mo:Expected error in mat bytevector-u64-native-set!: "incorrect number of arguments to #<procedure bytevector-u64-native-set!>".
-  bytevector.mo:Expected error in mat bytevector-u64-native-set!: "bytevector-u64-native-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-u64-native-set!: "bytevector-u64-native-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-u64-native-set!: "bytevector-u64-native-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+  bytevector.mo:Expected error in mat bytevector-u64-native-set!: "bytevector-u64-native-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-u64-native-set!: "bytevector-u64-native-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 ***************
-*** 2789,2798 ****
+*** 2796,2805 ****
   bytevector.mo:Expected error in mat bytevector-u64-native-set!: "bytevector-u64-native-set!: invalid value <int>".
   bytevector.mo:Expected error in mat bytevector-u64-native-set!: "bytevector-u64-native-set!: invalid value -1".
   bytevector.mo:Expected error in mat bytevector-u64-native-set!: "bytevector-u64-native-set!: invalid value "hello"".
@@ -3103,7 +3113,7 @@
   bytevector.mo:Expected error in mat bytevector-s64-ref: "bytevector-s64-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-s64-ref: "bytevector-s64-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-s64-ref: "bytevector-s64-ref: invalid index -1 for bytevector #vu8(0 0 0 0 0 0 ...)".
---- 2789,2798 ----
+--- 2796,2805 ----
   bytevector.mo:Expected error in mat bytevector-u64-native-set!: "bytevector-u64-native-set!: invalid value <int>".
   bytevector.mo:Expected error in mat bytevector-u64-native-set!: "bytevector-u64-native-set!: invalid value -1".
   bytevector.mo:Expected error in mat bytevector-u64-native-set!: "bytevector-u64-native-set!: invalid value "hello"".
@@ -3115,7 +3125,7 @@
   bytevector.mo:Expected error in mat bytevector-s64-ref: "bytevector-s64-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-s64-ref: "bytevector-s64-ref: invalid index -1 for bytevector #vu8(0 0 0 0 0 0 ...)".
 ***************
-*** 2808,2817 ****
+*** 2815,2824 ****
   bytevector.mo:Expected error in mat bytevector-s64-ref: "bytevector-s64-ref: unrecognized endianness (quote bonkers)".
   bytevector.mo:Expected error in mat bytevector-s64-ref: "bytevector-s64-ref: unrecognized endianness get-real".
   bytevector.mo:Expected error in mat bytevector-s64-ref: "bytevector-s64-ref: unrecognized endianness 1e23".
@@ -3126,7 +3136,7 @@
   bytevector.mo:Expected error in mat bytevector-u64-ref: "bytevector-u64-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-u64-ref: "bytevector-u64-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-u64-ref: "bytevector-u64-ref: invalid index -1 for bytevector #vu8(0 0 0 0 0 0 ...)".
---- 2808,2817 ----
+--- 2815,2824 ----
   bytevector.mo:Expected error in mat bytevector-s64-ref: "bytevector-s64-ref: unrecognized endianness (quote bonkers)".
   bytevector.mo:Expected error in mat bytevector-s64-ref: "bytevector-s64-ref: unrecognized endianness get-real".
   bytevector.mo:Expected error in mat bytevector-s64-ref: "bytevector-s64-ref: unrecognized endianness 1e23".
@@ -3138,7 +3148,7 @@
   bytevector.mo:Expected error in mat bytevector-u64-ref: "bytevector-u64-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-u64-ref: "bytevector-u64-ref: invalid index -1 for bytevector #vu8(0 0 0 0 0 0 ...)".
 ***************
-*** 2827,2837 ****
+*** 2834,2844 ****
   bytevector.mo:Expected error in mat bytevector-u64-ref: "bytevector-u64-ref: unrecognized endianness (quote bonkers)".
   bytevector.mo:Expected error in mat bytevector-u64-ref: "bytevector-u64-ref: unrecognized endianness get-real".
   bytevector.mo:Expected error in mat bytevector-u64-ref: "bytevector-u64-ref: unrecognized endianness 1e23".
@@ -3147,10 +3157,10 @@
 ! bytevector.mo:Expected error in mat bytevector-s64-set!: "incorrect argument count in call (bytevector-s64-set! $v1 0)".
 ! bytevector.mo:Expected error in mat bytevector-s64-set!: "incorrect argument count in call (bytevector-s64-set! $v1 0 0)".
 ! bytevector.mo:Expected error in mat bytevector-s64-set!: "incorrect argument count in call (bytevector-s64-set! $v1 0 0 (quote big) 15)".
-  bytevector.mo:Expected error in mat bytevector-s64-set!: "bytevector-s64-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-s64-set!: "bytevector-s64-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-s64-set!: "bytevector-s64-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+  bytevector.mo:Expected error in mat bytevector-s64-set!: "bytevector-s64-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-s64-set!: "bytevector-s64-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
---- 2827,2837 ----
+--- 2834,2844 ----
   bytevector.mo:Expected error in mat bytevector-u64-ref: "bytevector-u64-ref: unrecognized endianness (quote bonkers)".
   bytevector.mo:Expected error in mat bytevector-u64-ref: "bytevector-u64-ref: unrecognized endianness get-real".
   bytevector.mo:Expected error in mat bytevector-u64-ref: "bytevector-u64-ref: unrecognized endianness 1e23".
@@ -3159,11 +3169,11 @@
 ! bytevector.mo:Expected error in mat bytevector-s64-set!: "incorrect number of arguments to #<procedure bytevector-s64-set!>".
 ! bytevector.mo:Expected error in mat bytevector-s64-set!: "incorrect number of arguments to #<procedure bytevector-s64-set!>".
 ! bytevector.mo:Expected error in mat bytevector-s64-set!: "incorrect number of arguments to #<procedure bytevector-s64-set!>".
-  bytevector.mo:Expected error in mat bytevector-s64-set!: "bytevector-s64-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-s64-set!: "bytevector-s64-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-s64-set!: "bytevector-s64-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+  bytevector.mo:Expected error in mat bytevector-s64-set!: "bytevector-s64-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-s64-set!: "bytevector-s64-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 ***************
-*** 2850,2860 ****
+*** 2857,2867 ****
   bytevector.mo:Expected error in mat bytevector-s64-set!: "bytevector-s64-set!: unrecognized endianness gorgeous".
   bytevector.mo:Expected error in mat bytevector-s64-set!: "bytevector-s64-set!: unrecognized endianness #(ravenous)".
   bytevector.mo:Expected error in mat bytevector-s64-set!: "bytevector-s64-set!: unrecognized endianness #t".
@@ -3172,10 +3182,10 @@
 ! bytevector.mo:Expected error in mat bytevector-u64-set!: "incorrect argument count in call (bytevector-u64-set! $v1 0)".
 ! bytevector.mo:Expected error in mat bytevector-u64-set!: "incorrect argument count in call (bytevector-u64-set! $v1 0 0)".
 ! bytevector.mo:Expected error in mat bytevector-u64-set!: "incorrect argument count in call (bytevector-u64-set! $v1 0 0 (quote big) 15)".
-  bytevector.mo:Expected error in mat bytevector-u64-set!: "bytevector-u64-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-u64-set!: "bytevector-u64-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-u64-set!: "bytevector-u64-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+  bytevector.mo:Expected error in mat bytevector-u64-set!: "bytevector-u64-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-u64-set!: "bytevector-u64-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
---- 2850,2860 ----
+--- 2857,2867 ----
   bytevector.mo:Expected error in mat bytevector-s64-set!: "bytevector-s64-set!: unrecognized endianness gorgeous".
   bytevector.mo:Expected error in mat bytevector-s64-set!: "bytevector-s64-set!: unrecognized endianness #(ravenous)".
   bytevector.mo:Expected error in mat bytevector-s64-set!: "bytevector-s64-set!: unrecognized endianness #t".
@@ -3184,11 +3194,11 @@
 ! bytevector.mo:Expected error in mat bytevector-u64-set!: "incorrect number of arguments to #<procedure bytevector-u64-set!>".
 ! bytevector.mo:Expected error in mat bytevector-u64-set!: "incorrect number of arguments to #<procedure bytevector-u64-set!>".
 ! bytevector.mo:Expected error in mat bytevector-u64-set!: "incorrect number of arguments to #<procedure bytevector-u64-set!>".
-  bytevector.mo:Expected error in mat bytevector-u64-set!: "bytevector-u64-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-u64-set!: "bytevector-u64-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-u64-set!: "bytevector-u64-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+  bytevector.mo:Expected error in mat bytevector-u64-set!: "bytevector-u64-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-u64-set!: "bytevector-u64-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 ***************
-*** 2873,2881 ****
+*** 2880,2888 ****
   bytevector.mo:Expected error in mat bytevector-u64-set!: "bytevector-u64-set!: unrecognized endianness gorgeous".
   bytevector.mo:Expected error in mat bytevector-u64-set!: "bytevector-u64-set!: unrecognized endianness #(ravenous)".
   bytevector.mo:Expected error in mat bytevector-u64-set!: "bytevector-u64-set!: unrecognized endianness #t".
@@ -3198,7 +3208,7 @@
   bytevector.mo:Expected error in mat bytevector-ieee-single-native-ref: "bytevector-ieee-single-native-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-ieee-single-native-ref: "bytevector-ieee-single-native-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-ieee-single-native-ref: "bytevector-ieee-single-native-ref: invalid index -1 for bytevector #vu8(0 0 0 0 0 0 ...)".
---- 2873,2881 ----
+--- 2880,2888 ----
   bytevector.mo:Expected error in mat bytevector-u64-set!: "bytevector-u64-set!: unrecognized endianness gorgeous".
   bytevector.mo:Expected error in mat bytevector-u64-set!: "bytevector-u64-set!: unrecognized endianness #(ravenous)".
   bytevector.mo:Expected error in mat bytevector-u64-set!: "bytevector-u64-set!: unrecognized endianness #t".
@@ -3209,7 +3219,7 @@
   bytevector.mo:Expected error in mat bytevector-ieee-single-native-ref: "bytevector-ieee-single-native-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-ieee-single-native-ref: "bytevector-ieee-single-native-ref: invalid index -1 for bytevector #vu8(0 0 0 0 0 0 ...)".
 ***************
-*** 2911,2919 ****
+*** 2918,2926 ****
   bytevector.mo:Expected error in mat bytevector-ieee-single-native-ref: "bytevector-ieee-single-native-ref: invalid index 38 for bytevector #vu8(0 0 0 0 0 0 ...)".
   bytevector.mo:Expected error in mat bytevector-ieee-single-native-ref: "bytevector-ieee-single-native-ref: invalid index 39 for bytevector #vu8(0 0 0 0 0 0 ...)".
   bytevector.mo:Expected error in mat bytevector-ieee-single-native-ref: "bytevector-ieee-single-native-ref: invalid index 4.0 for bytevector #vu8(0 0 0 0 0 0 ...)".
@@ -3219,7 +3229,7 @@
   bytevector.mo:Expected error in mat bytevector-ieee-double-native-ref: "bytevector-ieee-double-native-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-ieee-double-native-ref: "bytevector-ieee-double-native-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-ieee-double-native-ref: "bytevector-ieee-double-native-ref: invalid index -1 for bytevector #vu8(0 0 0 0 0 0 ...)".
---- 2911,2919 ----
+--- 2918,2926 ----
   bytevector.mo:Expected error in mat bytevector-ieee-single-native-ref: "bytevector-ieee-single-native-ref: invalid index 38 for bytevector #vu8(0 0 0 0 0 0 ...)".
   bytevector.mo:Expected error in mat bytevector-ieee-single-native-ref: "bytevector-ieee-single-native-ref: invalid index 39 for bytevector #vu8(0 0 0 0 0 0 ...)".
   bytevector.mo:Expected error in mat bytevector-ieee-single-native-ref: "bytevector-ieee-single-native-ref: invalid index 4.0 for bytevector #vu8(0 0 0 0 0 0 ...)".
@@ -3230,7 +3240,7 @@
   bytevector.mo:Expected error in mat bytevector-ieee-double-native-ref: "bytevector-ieee-double-native-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-ieee-double-native-ref: "bytevector-ieee-double-native-ref: invalid index -1 for bytevector #vu8(0 0 0 0 0 0 ...)".
 ***************
-*** 2953,2962 ****
+*** 2960,2969 ****
   bytevector.mo:Expected error in mat bytevector-ieee-double-native-ref: "bytevector-ieee-double-native-ref: invalid index 70 for bytevector #vu8(0 0 0 0 0 0 ...)".
   bytevector.mo:Expected error in mat bytevector-ieee-double-native-ref: "bytevector-ieee-double-native-ref: invalid index 71 for bytevector #vu8(0 0 0 0 0 0 ...)".
   bytevector.mo:Expected error in mat bytevector-ieee-double-native-ref: "bytevector-ieee-double-native-ref: invalid index 4.0 for bytevector #vu8(0 0 0 0 0 0 ...)".
@@ -3238,10 +3248,10 @@
 ! bytevector.mo:Expected error in mat bytevector-ieee-single-native-set!: "incorrect argument count in call (bytevector-ieee-single-native-set! $v1)".
 ! bytevector.mo:Expected error in mat bytevector-ieee-single-native-set!: "incorrect argument count in call (bytevector-ieee-single-native-set! $v1 0)".
 ! bytevector.mo:Expected error in mat bytevector-ieee-single-native-set!: "incorrect argument count in call (bytevector-ieee-single-native-set! $v1 0 0.0 0.0)".
-  bytevector.mo:Expected error in mat bytevector-ieee-single-native-set!: "bytevector-ieee-single-native-set!: #(3 252 5 0 0 0 ...) is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-ieee-single-native-set!: "bytevector-ieee-single-native-set!: #(3 252 5 0 0 0 ...) is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-ieee-single-native-set!: "bytevector-ieee-single-native-set!: #(3 252 5 0 0 0 ...) is not a mutable bytevector".
+  bytevector.mo:Expected error in mat bytevector-ieee-single-native-set!: "bytevector-ieee-single-native-set!: #(3 252 5 0 0 0 ...) is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-ieee-single-native-set!: "bytevector-ieee-single-native-set!: invalid index -1 for bytevector #vu8(235 235 235 235 235 235 ...)".
---- 2953,2962 ----
+--- 2960,2969 ----
   bytevector.mo:Expected error in mat bytevector-ieee-double-native-ref: "bytevector-ieee-double-native-ref: invalid index 70 for bytevector #vu8(0 0 0 0 0 0 ...)".
   bytevector.mo:Expected error in mat bytevector-ieee-double-native-ref: "bytevector-ieee-double-native-ref: invalid index 71 for bytevector #vu8(0 0 0 0 0 0 ...)".
   bytevector.mo:Expected error in mat bytevector-ieee-double-native-ref: "bytevector-ieee-double-native-ref: invalid index 4.0 for bytevector #vu8(0 0 0 0 0 0 ...)".
@@ -3249,11 +3259,11 @@
 ! bytevector.mo:Expected error in mat bytevector-ieee-single-native-set!: "incorrect number of arguments to #<procedure bytevector-ieee-single-native-set!>".
 ! bytevector.mo:Expected error in mat bytevector-ieee-single-native-set!: "incorrect number of arguments to #<procedure bytevector-ieee-single-native-set!>".
 ! bytevector.mo:Expected error in mat bytevector-ieee-single-native-set!: "incorrect number of arguments to #<procedure bytevector-ieee-single-native-set!>".
-  bytevector.mo:Expected error in mat bytevector-ieee-single-native-set!: "bytevector-ieee-single-native-set!: #(3 252 5 0 0 0 ...) is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-ieee-single-native-set!: "bytevector-ieee-single-native-set!: #(3 252 5 0 0 0 ...) is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-ieee-single-native-set!: "bytevector-ieee-single-native-set!: #(3 252 5 0 0 0 ...) is not a mutable bytevector".
+  bytevector.mo:Expected error in mat bytevector-ieee-single-native-set!: "bytevector-ieee-single-native-set!: #(3 252 5 0 0 0 ...) is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-ieee-single-native-set!: "bytevector-ieee-single-native-set!: invalid index -1 for bytevector #vu8(235 235 235 235 235 235 ...)".
 ***************
-*** 2990,2999 ****
+*** 2997,3006 ****
   bytevector.mo:Expected error in mat bytevector-ieee-single-native-set!: "bytevector-ieee-single-native-set!: 1.0+0.0i is not a real number".
   bytevector.mo:Expected error in mat bytevector-ieee-single-native-set!: "bytevector-ieee-single-native-set!: 1.0-0.0i is not a real number".
   bytevector.mo:Expected error in mat bytevector-ieee-single-native-set!: "bytevector-ieee-single-native-set!: "oops" is not a real number".
@@ -3261,10 +3271,10 @@
 ! bytevector.mo:Expected error in mat bytevector-ieee-double-native-set!: "incorrect argument count in call (bytevector-ieee-double-native-set! $v1)".
 ! bytevector.mo:Expected error in mat bytevector-ieee-double-native-set!: "incorrect argument count in call (bytevector-ieee-double-native-set! $v1 0)".
 ! bytevector.mo:Expected error in mat bytevector-ieee-double-native-set!: "incorrect argument count in call (bytevector-ieee-double-native-set! $v1 0 0.0 0.0)".
-  bytevector.mo:Expected error in mat bytevector-ieee-double-native-set!: "bytevector-ieee-double-native-set!: #(3 252 5 0 0 0 ...) is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-ieee-double-native-set!: "bytevector-ieee-double-native-set!: #(3 252 5 0 0 0 ...) is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-ieee-double-native-set!: "bytevector-ieee-double-native-set!: #(3 252 5 0 0 0 ...) is not a mutable bytevector".
+  bytevector.mo:Expected error in mat bytevector-ieee-double-native-set!: "bytevector-ieee-double-native-set!: #(3 252 5 0 0 0 ...) is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-ieee-double-native-set!: "bytevector-ieee-double-native-set!: invalid index -1 for bytevector #vu8(235 235 235 235 235 235 ...)".
---- 2990,2999 ----
+--- 2997,3006 ----
   bytevector.mo:Expected error in mat bytevector-ieee-single-native-set!: "bytevector-ieee-single-native-set!: 1.0+0.0i is not a real number".
   bytevector.mo:Expected error in mat bytevector-ieee-single-native-set!: "bytevector-ieee-single-native-set!: 1.0-0.0i is not a real number".
   bytevector.mo:Expected error in mat bytevector-ieee-single-native-set!: "bytevector-ieee-single-native-set!: "oops" is not a real number".
@@ -3272,11 +3282,11 @@
 ! bytevector.mo:Expected error in mat bytevector-ieee-double-native-set!: "incorrect number of arguments to #<procedure bytevector-ieee-double-native-set!>".
 ! bytevector.mo:Expected error in mat bytevector-ieee-double-native-set!: "incorrect number of arguments to #<procedure bytevector-ieee-double-native-set!>".
 ! bytevector.mo:Expected error in mat bytevector-ieee-double-native-set!: "incorrect number of arguments to #<procedure bytevector-ieee-double-native-set!>".
-  bytevector.mo:Expected error in mat bytevector-ieee-double-native-set!: "bytevector-ieee-double-native-set!: #(3 252 5 0 0 0 ...) is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-ieee-double-native-set!: "bytevector-ieee-double-native-set!: #(3 252 5 0 0 0 ...) is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-ieee-double-native-set!: "bytevector-ieee-double-native-set!: #(3 252 5 0 0 0 ...) is not a mutable bytevector".
+  bytevector.mo:Expected error in mat bytevector-ieee-double-native-set!: "bytevector-ieee-double-native-set!: #(3 252 5 0 0 0 ...) is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-ieee-double-native-set!: "bytevector-ieee-double-native-set!: invalid index -1 for bytevector #vu8(235 235 235 235 235 235 ...)".
 ***************
-*** 3039,3048 ****
+*** 3046,3055 ****
   bytevector.mo:Expected error in mat bytevector-ieee-double-native-set!: "bytevector-ieee-double-native-set!: 1.0+0.0i is not a real number".
   bytevector.mo:Expected error in mat bytevector-ieee-double-native-set!: "bytevector-ieee-double-native-set!: 1.0-0.0i is not a real number".
   bytevector.mo:Expected error in mat bytevector-ieee-double-native-set!: "bytevector-ieee-double-native-set!: "oops" is not a real number".
@@ -3287,7 +3297,7 @@
   bytevector.mo:Expected error in mat bytevector-ieee-single-ref: "bytevector-ieee-single-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-ieee-single-ref: "bytevector-ieee-single-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-ieee-single-ref: "bytevector-ieee-single-ref: invalid index -1 for bytevector #vu8(0 0 0 0 199 0 ...)".
---- 3039,3048 ----
+--- 3046,3055 ----
   bytevector.mo:Expected error in mat bytevector-ieee-double-native-set!: "bytevector-ieee-double-native-set!: 1.0+0.0i is not a real number".
   bytevector.mo:Expected error in mat bytevector-ieee-double-native-set!: "bytevector-ieee-double-native-set!: 1.0-0.0i is not a real number".
   bytevector.mo:Expected error in mat bytevector-ieee-double-native-set!: "bytevector-ieee-double-native-set!: "oops" is not a real number".
@@ -3299,7 +3309,7 @@
   bytevector.mo:Expected error in mat bytevector-ieee-single-ref: "bytevector-ieee-single-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-ieee-single-ref: "bytevector-ieee-single-ref: invalid index -1 for bytevector #vu8(0 0 0 0 199 0 ...)".
 ***************
-*** 3054,3063 ****
+*** 3061,3070 ****
   bytevector.mo:Expected error in mat bytevector-ieee-single-ref: "bytevector-ieee-single-ref: unrecognized endianness "nuts"".
   bytevector.mo:Expected error in mat bytevector-ieee-single-ref: "bytevector-ieee-single-ref: unrecognized endianness crazy".
   bytevector.mo:Expected error in mat bytevector-ieee-single-ref: "bytevector-ieee-single-ref: unrecognized endianness 35".
@@ -3310,7 +3320,7 @@
   bytevector.mo:Expected error in mat bytevector-ieee-double-ref: "bytevector-ieee-double-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-ieee-double-ref: "bytevector-ieee-double-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-ieee-double-ref: "bytevector-ieee-double-ref: invalid index -1 for bytevector #vu8(0 0 0 0 0 0 ...)".
---- 3054,3063 ----
+--- 3061,3070 ----
   bytevector.mo:Expected error in mat bytevector-ieee-single-ref: "bytevector-ieee-single-ref: unrecognized endianness "nuts"".
   bytevector.mo:Expected error in mat bytevector-ieee-single-ref: "bytevector-ieee-single-ref: unrecognized endianness crazy".
   bytevector.mo:Expected error in mat bytevector-ieee-single-ref: "bytevector-ieee-single-ref: unrecognized endianness 35".
@@ -3322,7 +3332,7 @@
   bytevector.mo:Expected error in mat bytevector-ieee-double-ref: "bytevector-ieee-double-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-ieee-double-ref: "bytevector-ieee-double-ref: invalid index -1 for bytevector #vu8(0 0 0 0 0 0 ...)".
 ***************
-*** 3073,3083 ****
+*** 3080,3090 ****
   bytevector.mo:Expected error in mat bytevector-ieee-double-ref: "bytevector-ieee-double-ref: unrecognized endianness "nuts"".
   bytevector.mo:Expected error in mat bytevector-ieee-double-ref: "bytevector-ieee-double-ref: unrecognized endianness crazy".
   bytevector.mo:Expected error in mat bytevector-ieee-double-ref: "bytevector-ieee-double-ref: unrecognized endianness 35".
@@ -3331,10 +3341,10 @@
 ! bytevector.mo:Expected error in mat bytevector-ieee-single-set!: "incorrect argument count in call (bytevector-ieee-single-set! $v1 0)".
 ! bytevector.mo:Expected error in mat bytevector-ieee-single-set!: "incorrect argument count in call (bytevector-ieee-single-set! $v1 0 0.0)".
 ! bytevector.mo:Expected error in mat bytevector-ieee-single-set!: "incorrect argument count in call (bytevector-ieee-single-set! $v1 0 0.0 (quote big) (quote bigger))".
-  bytevector.mo:Expected error in mat bytevector-ieee-single-set!: "bytevector-ieee-single-set!: #(3 252 5 0 0 0 ...) is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-ieee-single-set!: "bytevector-ieee-single-set!: #(3 252 5 0 0 0 ...) is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-ieee-single-set!: "bytevector-ieee-single-set!: #(3 252 5 0 0 0 ...) is not a mutable bytevector".
+  bytevector.mo:Expected error in mat bytevector-ieee-single-set!: "bytevector-ieee-single-set!: #(3 252 5 0 0 0 ...) is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-ieee-single-set!: "bytevector-ieee-single-set!: invalid index -1 for bytevector #vu8(235 235 235 235 235 235 ...)".
---- 3073,3083 ----
+--- 3080,3090 ----
   bytevector.mo:Expected error in mat bytevector-ieee-double-ref: "bytevector-ieee-double-ref: unrecognized endianness "nuts"".
   bytevector.mo:Expected error in mat bytevector-ieee-double-ref: "bytevector-ieee-double-ref: unrecognized endianness crazy".
   bytevector.mo:Expected error in mat bytevector-ieee-double-ref: "bytevector-ieee-double-ref: unrecognized endianness 35".
@@ -3343,11 +3353,11 @@
 ! bytevector.mo:Expected error in mat bytevector-ieee-single-set!: "incorrect number of arguments to #<procedure bytevector-ieee-single-set!>".
 ! bytevector.mo:Expected error in mat bytevector-ieee-single-set!: "incorrect number of arguments to #<procedure bytevector-ieee-single-set!>".
 ! bytevector.mo:Expected error in mat bytevector-ieee-single-set!: "incorrect number of arguments to #<procedure bytevector-ieee-single-set!>".
-  bytevector.mo:Expected error in mat bytevector-ieee-single-set!: "bytevector-ieee-single-set!: #(3 252 5 0 0 0 ...) is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-ieee-single-set!: "bytevector-ieee-single-set!: #(3 252 5 0 0 0 ...) is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-ieee-single-set!: "bytevector-ieee-single-set!: #(3 252 5 0 0 0 ...) is not a mutable bytevector".
+  bytevector.mo:Expected error in mat bytevector-ieee-single-set!: "bytevector-ieee-single-set!: #(3 252 5 0 0 0 ...) is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-ieee-single-set!: "bytevector-ieee-single-set!: invalid index -1 for bytevector #vu8(235 235 235 235 235 235 ...)".
 ***************
-*** 3094,3104 ****
+*** 3101,3111 ****
   bytevector.mo:Expected error in mat bytevector-ieee-single-set!: "bytevector-ieee-single-set!: unrecognized endianness "ouch"".
   bytevector.mo:Expected error in mat bytevector-ieee-single-set!: "bytevector-ieee-single-set!: unrecognized endianness what?".
   bytevector.mo:Expected error in mat bytevector-ieee-single-set!: "bytevector-ieee-single-set!: unrecognized endianness #\newline".
@@ -3356,10 +3366,10 @@
 ! bytevector.mo:Expected error in mat bytevector-ieee-double-set!: "incorrect argument count in call (bytevector-ieee-double-set! $v1 0)".
 ! bytevector.mo:Expected error in mat bytevector-ieee-double-set!: "incorrect argument count in call (bytevector-ieee-double-set! $v1 0 0.0)".
 ! bytevector.mo:Expected error in mat bytevector-ieee-double-set!: "incorrect argument count in call (bytevector-ieee-double-set! $v1 0 0.0 (quote big) (quote bigger))".
-  bytevector.mo:Expected error in mat bytevector-ieee-double-set!: "bytevector-ieee-double-set!: #(3 252 5 0 0 0 ...) is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-ieee-double-set!: "bytevector-ieee-double-set!: #(3 252 5 0 0 0 ...) is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-ieee-double-set!: "bytevector-ieee-double-set!: #(3 252 5 0 0 0 ...) is not a mutable bytevector".
+  bytevector.mo:Expected error in mat bytevector-ieee-double-set!: "bytevector-ieee-double-set!: #(3 252 5 0 0 0 ...) is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-ieee-double-set!: "bytevector-ieee-double-set!: invalid index -1 for bytevector #vu8(235 235 235 235 235 235 ...)".
---- 3094,3104 ----
+--- 3101,3111 ----
   bytevector.mo:Expected error in mat bytevector-ieee-single-set!: "bytevector-ieee-single-set!: unrecognized endianness "ouch"".
   bytevector.mo:Expected error in mat bytevector-ieee-single-set!: "bytevector-ieee-single-set!: unrecognized endianness what?".
   bytevector.mo:Expected error in mat bytevector-ieee-single-set!: "bytevector-ieee-single-set!: unrecognized endianness #\newline".
@@ -3368,11 +3378,11 @@
 ! bytevector.mo:Expected error in mat bytevector-ieee-double-set!: "incorrect number of arguments to #<procedure bytevector-ieee-double-set!>".
 ! bytevector.mo:Expected error in mat bytevector-ieee-double-set!: "incorrect number of arguments to #<procedure bytevector-ieee-double-set!>".
 ! bytevector.mo:Expected error in mat bytevector-ieee-double-set!: "incorrect number of arguments to #<procedure bytevector-ieee-double-set!>".
-  bytevector.mo:Expected error in mat bytevector-ieee-double-set!: "bytevector-ieee-double-set!: #(3 252 5 0 0 0 ...) is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-ieee-double-set!: "bytevector-ieee-double-set!: #(3 252 5 0 0 0 ...) is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-ieee-double-set!: "bytevector-ieee-double-set!: #(3 252 5 0 0 0 ...) is not a mutable bytevector".
+  bytevector.mo:Expected error in mat bytevector-ieee-double-set!: "bytevector-ieee-double-set!: #(3 252 5 0 0 0 ...) is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-ieee-double-set!: "bytevector-ieee-double-set!: invalid index -1 for bytevector #vu8(235 235 235 235 235 235 ...)".
 ***************
-*** 3119,3129 ****
+*** 3126,3136 ****
   bytevector.mo:Expected error in mat bytevector-ieee-double-set!: "bytevector-ieee-double-set!: unrecognized endianness "ouch"".
   bytevector.mo:Expected error in mat bytevector-ieee-double-set!: "bytevector-ieee-double-set!: unrecognized endianness what?".
   bytevector.mo:Expected error in mat bytevector-ieee-double-set!: "bytevector-ieee-double-set!: unrecognized endianness #\newline".
@@ -3384,7 +3394,7 @@
   bytevector.mo:Expected error in mat bytevector-sint-ref: "bytevector-sint-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-sint-ref: "bytevector-sint-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-sint-ref: "bytevector-sint-ref: invalid index -1 for bytevector #vu8(0 0 0 0 0 0 ...)".
---- 3119,3129 ----
+--- 3126,3136 ----
   bytevector.mo:Expected error in mat bytevector-ieee-double-set!: "bytevector-ieee-double-set!: unrecognized endianness "ouch"".
   bytevector.mo:Expected error in mat bytevector-ieee-double-set!: "bytevector-ieee-double-set!: unrecognized endianness what?".
   bytevector.mo:Expected error in mat bytevector-ieee-double-set!: "bytevector-ieee-double-set!: unrecognized endianness #\newline".
@@ -3397,7 +3407,7 @@
   bytevector.mo:Expected error in mat bytevector-sint-ref: "bytevector-sint-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-sint-ref: "bytevector-sint-ref: invalid index -1 for bytevector #vu8(0 0 0 0 0 0 ...)".
 ***************
-*** 3158,3168 ****
+*** 3165,3175 ****
   bytevector.mo:Expected error in mat bytevector-sint-ref: "bytevector-sint-ref: invalid size 0".
   bytevector.mo:Expected error in mat bytevector-sint-ref: "bytevector-sint-ref: invalid size -1".
   bytevector.mo:Expected error in mat bytevector-sint-ref: "bytevector-sint-ref: invalid size byte".
@@ -3409,7 +3419,7 @@
   bytevector.mo:Expected error in mat bytevector-uint-ref: "bytevector-uint-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-uint-ref: "bytevector-uint-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-uint-ref: "bytevector-uint-ref: invalid index -1 for bytevector #vu8(0 0 0 0 0 0 ...)".
---- 3158,3168 ----
+--- 3165,3175 ----
   bytevector.mo:Expected error in mat bytevector-sint-ref: "bytevector-sint-ref: invalid size 0".
   bytevector.mo:Expected error in mat bytevector-sint-ref: "bytevector-sint-ref: invalid size -1".
   bytevector.mo:Expected error in mat bytevector-sint-ref: "bytevector-sint-ref: invalid size byte".
@@ -3422,7 +3432,7 @@
   bytevector.mo:Expected error in mat bytevector-uint-ref: "bytevector-uint-ref: #(3 252 5 0 0 0 ...) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector-uint-ref: "bytevector-uint-ref: invalid index -1 for bytevector #vu8(0 0 0 0 0 0 ...)".
 ***************
-*** 3200,3211 ****
+*** 3207,3218 ****
   bytevector.mo:Expected error in mat bytevector-uint-ref: "bytevector-uint-ref: invalid size <int> for bytevector #vu8(1 2 3 4)".
   bytevector.mo:Expected error in mat bytevector-uint-ref: "bytevector-uint-ref: invalid size -1".
   bytevector.mo:Expected error in mat bytevector-uint-ref: "bytevector-uint-ref: invalid size byte".
@@ -3432,10 +3442,10 @@
 ! bytevector.mo:Expected error in mat bytevector-sint-set!: "incorrect argument count in call (bytevector-sint-set! $v1 0 7)".
 ! bytevector.mo:Expected error in mat bytevector-sint-set!: "incorrect argument count in call (bytevector-sint-set! $v1 0 7 (quote big))".
 ! bytevector.mo:Expected error in mat bytevector-sint-set!: "incorrect argument count in call (bytevector-sint-set! $v1 0 7 (quote big) 5 ...)".
-  bytevector.mo:Expected error in mat bytevector-sint-set!: "bytevector-sint-set!: #(3 252 5 0 0 0 ...) is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-sint-set!: "bytevector-sint-set!: #(3 252 5 0 0 0 ...) is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-sint-set!: "bytevector-sint-set!: #(3 252 5 0 0 0 ...) is not a mutable bytevector".
+  bytevector.mo:Expected error in mat bytevector-sint-set!: "bytevector-sint-set!: #(3 252 5 0 0 0 ...) is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-sint-set!: "bytevector-sint-set!: invalid index -1 for bytevector #vu8(0 0 0 0 0 0 ...)".
---- 3200,3211 ----
+--- 3207,3218 ----
   bytevector.mo:Expected error in mat bytevector-uint-ref: "bytevector-uint-ref: invalid size <int> for bytevector #vu8(1 2 3 4)".
   bytevector.mo:Expected error in mat bytevector-uint-ref: "bytevector-uint-ref: invalid size -1".
   bytevector.mo:Expected error in mat bytevector-uint-ref: "bytevector-uint-ref: invalid size byte".
@@ -3445,11 +3455,11 @@
 ! bytevector.mo:Expected error in mat bytevector-sint-set!: "incorrect number of arguments to #<procedure bytevector-sint-set!>".
 ! bytevector.mo:Expected error in mat bytevector-sint-set!: "incorrect number of arguments to #<procedure bytevector-sint-set!>".
 ! bytevector.mo:Expected error in mat bytevector-sint-set!: "incorrect number of arguments to #<procedure bytevector-sint-set!>".
-  bytevector.mo:Expected error in mat bytevector-sint-set!: "bytevector-sint-set!: #(3 252 5 0 0 0 ...) is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-sint-set!: "bytevector-sint-set!: #(3 252 5 0 0 0 ...) is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-sint-set!: "bytevector-sint-set!: #(3 252 5 0 0 0 ...) is not a mutable bytevector".
+  bytevector.mo:Expected error in mat bytevector-sint-set!: "bytevector-sint-set!: #(3 252 5 0 0 0 ...) is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-sint-set!: "bytevector-sint-set!: invalid index -1 for bytevector #vu8(0 0 0 0 0 0 ...)".
 ***************
-*** 3264,3275 ****
+*** 3271,3282 ****
   bytevector.mo:Expected error in mat bytevector-sint-set!: "bytevector-sint-set!: invalid size 0".
   bytevector.mo:Expected error in mat bytevector-sint-set!: "bytevector-sint-set!: invalid size -1".
   bytevector.mo:Expected error in mat bytevector-sint-set!: "bytevector-sint-set!: invalid size byte".
@@ -3459,10 +3469,10 @@
 ! bytevector.mo:Expected error in mat bytevector-uint-set!: "incorrect argument count in call (bytevector-uint-set! $v1 0 7)".
 ! bytevector.mo:Expected error in mat bytevector-uint-set!: "incorrect argument count in call (bytevector-uint-set! $v1 0 7 (quote big))".
 ! bytevector.mo:Expected error in mat bytevector-uint-set!: "incorrect argument count in call (bytevector-uint-set! $v1 0 7 (quote big) 5 ...)".
-  bytevector.mo:Expected error in mat bytevector-uint-set!: "bytevector-uint-set!: #(3 252 5 0 0 0 ...) is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-uint-set!: "bytevector-uint-set!: #(3 252 5 0 0 0 ...) is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-uint-set!: "bytevector-uint-set!: #(3 252 5 0 0 0 ...) is not a mutable bytevector".
+  bytevector.mo:Expected error in mat bytevector-uint-set!: "bytevector-uint-set!: #(3 252 5 0 0 0 ...) is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-uint-set!: "bytevector-uint-set!: invalid index -1 for bytevector #vu8(0 0 0 0 0 0 ...)".
---- 3264,3275 ----
+--- 3271,3282 ----
   bytevector.mo:Expected error in mat bytevector-sint-set!: "bytevector-sint-set!: invalid size 0".
   bytevector.mo:Expected error in mat bytevector-sint-set!: "bytevector-sint-set!: invalid size -1".
   bytevector.mo:Expected error in mat bytevector-sint-set!: "bytevector-sint-set!: invalid size byte".
@@ -3472,11 +3482,11 @@
 ! bytevector.mo:Expected error in mat bytevector-uint-set!: "incorrect number of arguments to #<procedure bytevector-uint-set!>".
 ! bytevector.mo:Expected error in mat bytevector-uint-set!: "incorrect number of arguments to #<procedure bytevector-uint-set!>".
 ! bytevector.mo:Expected error in mat bytevector-uint-set!: "incorrect number of arguments to #<procedure bytevector-uint-set!>".
-  bytevector.mo:Expected error in mat bytevector-uint-set!: "bytevector-uint-set!: #(3 252 5 0 0 0 ...) is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-uint-set!: "bytevector-uint-set!: #(3 252 5 0 0 0 ...) is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-uint-set!: "bytevector-uint-set!: #(3 252 5 0 0 0 ...) is not a mutable bytevector".
+  bytevector.mo:Expected error in mat bytevector-uint-set!: "bytevector-uint-set!: #(3 252 5 0 0 0 ...) is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-uint-set!: "bytevector-uint-set!: invalid index -1 for bytevector #vu8(0 0 0 0 0 0 ...)".
 ***************
-*** 3328,3343 ****
+*** 3335,3350 ****
   bytevector.mo:Expected error in mat bytevector-uint-set!: "bytevector-uint-set!: invalid size 0".
   bytevector.mo:Expected error in mat bytevector-uint-set!: "bytevector-uint-set!: invalid size -1".
   bytevector.mo:Expected error in mat bytevector-uint-set!: "bytevector-uint-set!: invalid size byte".
@@ -3491,9 +3501,9 @@
 ! bytevector.mo:Expected error in mat bytevector-copy!: "incorrect argument count in call (bytevector-copy! $v2 3 $v1 1)".
 ! bytevector.mo:Expected error in mat bytevector-copy!: "incorrect argument count in call (bytevector-copy! $v2 3 $v1 1 2 ...)".
   bytevector.mo:Expected error in mat bytevector-copy!: "bytevector-copy!: 0 is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-copy!: "bytevector-copy!: #(1 2 3) is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-copy!: "bytevector-copy!: #(1 2 3) is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-copy!: "bytevector-copy!: invalid start value -1".
---- 3328,3343 ----
+--- 3335,3350 ----
   bytevector.mo:Expected error in mat bytevector-uint-set!: "bytevector-uint-set!: invalid size 0".
   bytevector.mo:Expected error in mat bytevector-uint-set!: "bytevector-uint-set!: invalid size -1".
   bytevector.mo:Expected error in mat bytevector-uint-set!: "bytevector-uint-set!: invalid size byte".
@@ -3508,39 +3518,39 @@
 ! bytevector.mo:Expected error in mat bytevector-copy!: "incorrect number of arguments to #<procedure bytevector-copy!>".
 ! bytevector.mo:Expected error in mat bytevector-copy!: "incorrect number of arguments to #<procedure bytevector-copy!>".
   bytevector.mo:Expected error in mat bytevector-copy!: "bytevector-copy!: 0 is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-copy!: "bytevector-copy!: #(1 2 3) is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-copy!: "bytevector-copy!: #(1 2 3) is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-copy!: "bytevector-copy!: invalid start value -1".
 ***************
-*** 3361,3369 ****
+*** 3368,3376 ****
   bytevector.mo:Expected error in mat bytevector-copy!: "bytevector-copy!: index 4 + count 1 is beyond the end of #vu8(1 2 3 4)".
   bytevector.mo:Expected error in mat bytevector-copy!: "bytevector-copy!: index 0 + count 500 is beyond the end of #vu8(255 254 253 252 251 250 ...)".
   bytevector.mo:Expected error in mat bytevector-copy!: "bytevector-copy!: index 500 + count 0 is beyond the end of #vu8(255 254 253 252 251 250 ...)".
 ! bytevector.mo:Expected error in mat bytevector-truncate!: "incorrect argument count in call (bytevector-truncate!)".
 ! bytevector.mo:Expected error in mat bytevector-truncate!: "incorrect argument count in call (bytevector-truncate! $v)".
 ! bytevector.mo:Expected error in mat bytevector-truncate!: "incorrect argument count in call (bytevector-truncate! $v 3 15)".
-  bytevector.mo:Expected error in mat bytevector-truncate!: "bytevector-truncate!: 0 is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-truncate!: "bytevector-truncate!: "abc" is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-truncate!: "bytevector-truncate!: 0 is not a mutable bytevector".
+  bytevector.mo:Expected error in mat bytevector-truncate!: "bytevector-truncate!: "abc" is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-truncate!: "bytevector-truncate!: invalid new length -1 for #vu8(1 2 3 4 5 6 ...)".
---- 3361,3369 ----
+--- 3368,3376 ----
   bytevector.mo:Expected error in mat bytevector-copy!: "bytevector-copy!: index 4 + count 1 is beyond the end of #vu8(1 2 3 4)".
   bytevector.mo:Expected error in mat bytevector-copy!: "bytevector-copy!: index 0 + count 500 is beyond the end of #vu8(255 254 253 252 251 250 ...)".
   bytevector.mo:Expected error in mat bytevector-copy!: "bytevector-copy!: index 500 + count 0 is beyond the end of #vu8(255 254 253 252 251 250 ...)".
 ! bytevector.mo:Expected error in mat bytevector-truncate!: "incorrect number of arguments to #<procedure bytevector-truncate!>".
 ! bytevector.mo:Expected error in mat bytevector-truncate!: "incorrect number of arguments to #<procedure bytevector-truncate!>".
 ! bytevector.mo:Expected error in mat bytevector-truncate!: "incorrect number of arguments to #<procedure bytevector-truncate!>".
-  bytevector.mo:Expected error in mat bytevector-truncate!: "bytevector-truncate!: 0 is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-truncate!: "bytevector-truncate!: "abc" is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-truncate!: "bytevector-truncate!: 0 is not a mutable bytevector".
+  bytevector.mo:Expected error in mat bytevector-truncate!: "bytevector-truncate!: "abc" is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-truncate!: "bytevector-truncate!: invalid new length -1 for #vu8(1 2 3 4 5 6 ...)".
 ***************
-*** 3371,3411 ****
+*** 3378,3418 ****
   bytevector.mo:Expected error in mat bytevector-truncate!: "bytevector-truncate!: invalid new length 1000 for #vu8(1 2 3 4 5 6 ...)".
   bytevector.mo:Expected error in mat bytevector-truncate!: "bytevector-truncate!: invalid new length <int> for #vu8(1 2 3 4 5 6 ...)".
   bytevector.mo:Expected error in mat bytevector-truncate!: "bytevector-truncate!: invalid new length a for #vu8(1 2 3 4 5 6 ...)".
 ! bytevector.mo:Expected error in mat bytevector-fill!: "incorrect argument count in call (bytevector-fill!)".
 ! bytevector.mo:Expected error in mat bytevector-fill!: "incorrect argument count in call (bytevector-fill! $v1)".
 ! bytevector.mo:Expected error in mat bytevector-fill!: "incorrect argument count in call (bytevector-fill! $v1 0 0)".
-  bytevector.mo:Expected error in mat bytevector-fill!: "bytevector-fill!: a is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-fill!: "bytevector-fill!: #(1) is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-fill!: "bytevector-fill!: a is not a mutable bytevector".
+  bytevector.mo:Expected error in mat bytevector-fill!: "bytevector-fill!: #(1) is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-fill!: "bytevector-fill!: -129 is not a valid fill value".
   bytevector.mo:Expected error in mat bytevector-fill!: "bytevector-fill!: 256 is not a valid fill value".
   bytevector.mo:Expected error in mat bytevector-fill!: "bytevector-fill!: a is not a valid fill value".
@@ -3574,15 +3584,15 @@
   bytevector.mo:Expected error in mat sint-list->bytevector: "sint-list->bytevector: #(a b c) is not a proper list".
   bytevector.mo:Expected error in mat sint-list->bytevector: "sint-list->bytevector: #(a b c) is not a proper list".
   bytevector.mo:Expected error in mat sint-list->bytevector: "sint-list->bytevector: (1 2 . 3) is not a proper list".
---- 3371,3411 ----
+--- 3378,3418 ----
   bytevector.mo:Expected error in mat bytevector-truncate!: "bytevector-truncate!: invalid new length 1000 for #vu8(1 2 3 4 5 6 ...)".
   bytevector.mo:Expected error in mat bytevector-truncate!: "bytevector-truncate!: invalid new length <int> for #vu8(1 2 3 4 5 6 ...)".
   bytevector.mo:Expected error in mat bytevector-truncate!: "bytevector-truncate!: invalid new length a for #vu8(1 2 3 4 5 6 ...)".
 ! bytevector.mo:Expected error in mat bytevector-fill!: "incorrect number of arguments to #<procedure bytevector-fill!>".
 ! bytevector.mo:Expected error in mat bytevector-fill!: "incorrect number of arguments to #<procedure bytevector-fill!>".
 ! bytevector.mo:Expected error in mat bytevector-fill!: "incorrect number of arguments to #<procedure bytevector-fill!>".
-  bytevector.mo:Expected error in mat bytevector-fill!: "bytevector-fill!: a is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector-fill!: "bytevector-fill!: #(1) is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector-fill!: "bytevector-fill!: a is not a mutable bytevector".
+  bytevector.mo:Expected error in mat bytevector-fill!: "bytevector-fill!: #(1) is not a mutable bytevector".
   bytevector.mo:Expected error in mat bytevector-fill!: "bytevector-fill!: -129 is not a valid fill value".
   bytevector.mo:Expected error in mat bytevector-fill!: "bytevector-fill!: 256 is not a valid fill value".
   bytevector.mo:Expected error in mat bytevector-fill!: "bytevector-fill!: a is not a valid fill value".
@@ -3617,7 +3627,7 @@
   bytevector.mo:Expected error in mat sint-list->bytevector: "sint-list->bytevector: #(a b c) is not a proper list".
   bytevector.mo:Expected error in mat sint-list->bytevector: "sint-list->bytevector: (1 2 . 3) is not a proper list".
 ***************
-*** 3444,3452 ****
+*** 3451,3459 ****
   bytevector.mo:Expected error in mat sint-list->bytevector: "sint-list->bytevector: invalid size 0".
   bytevector.mo:Expected error in mat sint-list->bytevector: "sint-list->bytevector: invalid size 1.0".
   bytevector.mo:Expected error in mat sint-list->bytevector: "sint-list->bytevector: invalid size "oops"".
@@ -3627,7 +3637,7 @@
   bytevector.mo:Expected error in mat uint-list->bytevector: "uint-list->bytevector: #(a b c) is not a proper list".
   bytevector.mo:Expected error in mat uint-list->bytevector: "uint-list->bytevector: #(a b c) is not a proper list".
   bytevector.mo:Expected error in mat uint-list->bytevector: "uint-list->bytevector: (1 2 . 3) is not a proper list".
---- 3444,3452 ----
+--- 3451,3459 ----
   bytevector.mo:Expected error in mat sint-list->bytevector: "sint-list->bytevector: invalid size 0".
   bytevector.mo:Expected error in mat sint-list->bytevector: "sint-list->bytevector: invalid size 1.0".
   bytevector.mo:Expected error in mat sint-list->bytevector: "sint-list->bytevector: invalid size "oops"".
@@ -3638,7 +3648,7 @@
   bytevector.mo:Expected error in mat uint-list->bytevector: "uint-list->bytevector: #(a b c) is not a proper list".
   bytevector.mo:Expected error in mat uint-list->bytevector: "uint-list->bytevector: (1 2 . 3) is not a proper list".
 ***************
-*** 3485,3493 ****
+*** 3492,3500 ****
   bytevector.mo:Expected error in mat uint-list->bytevector: "uint-list->bytevector: invalid size 0".
   bytevector.mo:Expected error in mat uint-list->bytevector: "uint-list->bytevector: invalid size 1.0".
   bytevector.mo:Expected error in mat uint-list->bytevector: "uint-list->bytevector: invalid size "oops"".
@@ -3648,7 +3658,7 @@
   bytevector.mo:Expected error in mat bytevector->sint-list: "bytevector->sint-list: #(a b c) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector->sint-list: "bytevector->sint-list: #(a b c) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector->sint-list: "bytevector->sint-list: unrecognized endianness spam".
---- 3485,3493 ----
+--- 3492,3500 ----
   bytevector.mo:Expected error in mat uint-list->bytevector: "uint-list->bytevector: invalid size 0".
   bytevector.mo:Expected error in mat uint-list->bytevector: "uint-list->bytevector: invalid size 1.0".
   bytevector.mo:Expected error in mat uint-list->bytevector: "uint-list->bytevector: invalid size "oops"".
@@ -3659,7 +3669,7 @@
   bytevector.mo:Expected error in mat bytevector->sint-list: "bytevector->sint-list: #(a b c) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector->sint-list: "bytevector->sint-list: unrecognized endianness spam".
 ***************
-*** 3507,3515 ****
+*** 3514,3522 ****
   bytevector.mo:Expected error in mat bytevector->sint-list: "bytevector->sint-list: bytevector length 12 is not a multiple of size 10".
   bytevector.mo:Expected error in mat bytevector->sint-list: "bytevector->sint-list: bytevector length 12 is not a multiple of size 11".
   bytevector.mo:Expected error in mat bytevector->sint-list: "bytevector->sint-list: bytevector length 12 is not a multiple of size 50".
@@ -3669,7 +3679,7 @@
   bytevector.mo:Expected error in mat bytevector->uint-list: "bytevector->uint-list: #(a b c) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector->uint-list: "bytevector->uint-list: #(a b c) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector->uint-list: "bytevector->uint-list: unrecognized endianness spam".
---- 3507,3515 ----
+--- 3514,3522 ----
   bytevector.mo:Expected error in mat bytevector->sint-list: "bytevector->sint-list: bytevector length 12 is not a multiple of size 10".
   bytevector.mo:Expected error in mat bytevector->sint-list: "bytevector->sint-list: bytevector length 12 is not a multiple of size 11".
   bytevector.mo:Expected error in mat bytevector->sint-list: "bytevector->sint-list: bytevector length 12 is not a multiple of size 50".
@@ -3680,7 +3690,7 @@
   bytevector.mo:Expected error in mat bytevector->uint-list: "bytevector->uint-list: #(a b c) is not a bytevector".
   bytevector.mo:Expected error in mat bytevector->uint-list: "bytevector->uint-list: unrecognized endianness spam".
 ***************
-*** 3529,3548 ****
+*** 3536,3544 ****
   bytevector.mo:Expected error in mat bytevector->uint-list: "bytevector->uint-list: bytevector length 12 is not a multiple of size 10".
   bytevector.mo:Expected error in mat bytevector->uint-list: "bytevector->uint-list: bytevector length 12 is not a multiple of size 11".
   bytevector.mo:Expected error in mat bytevector->uint-list: "bytevector->uint-list: bytevector length 12 is not a multiple of size 50".
@@ -3690,6 +3700,19 @@
   bytevector.mo:Expected error in mat bytevector=?: "bytevector=?: a is not a bytevector".
   bytevector.mo:Expected error in mat bytevector=?: "bytevector=?: "a" is not a bytevector".
   bytevector.mo:Expected error in mat tspl/csug-examples: "invalid endianness "spam"".
+--- 3536,3544 ----
+  bytevector.mo:Expected error in mat bytevector->uint-list: "bytevector->uint-list: bytevector length 12 is not a multiple of size 10".
+  bytevector.mo:Expected error in mat bytevector->uint-list: "bytevector->uint-list: bytevector length 12 is not a multiple of size 11".
+  bytevector.mo:Expected error in mat bytevector->uint-list: "bytevector->uint-list: bytevector length 12 is not a multiple of size 50".
+! bytevector.mo:Expected error in mat bytevector=?: "incorrect number of arguments to #<procedure bytevector=?>".
+! bytevector.mo:Expected error in mat bytevector=?: "incorrect number of arguments to #<procedure bytevector=?>".
+! bytevector.mo:Expected error in mat bytevector=?: "incorrect number of arguments to #<procedure bytevector=?>".
+  bytevector.mo:Expected error in mat bytevector=?: "bytevector=?: a is not a bytevector".
+  bytevector.mo:Expected error in mat bytevector=?: "bytevector=?: "a" is not a bytevector".
+  bytevector.mo:Expected error in mat tspl/csug-examples: "invalid endianness "spam"".
+***************
+*** 3575,3586 ****
+  bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-truncate!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
   misc.mo:Expected error in mat compiler1: "variable i-am-not-bound is not bound".
   misc.mo:Expected error in mat compiler1: "attempt to apply non-procedure oops".
 ! misc.mo:Expected error in mat compiler1: "incorrect argument count in call (g (list))".
@@ -3701,16 +3724,8 @@
   misc.mo:Expected error in mat compiler3: "incorrect argument count in call (consumer 1 2) at line 3, char 19 of testfile.ss".
   misc.mo:Expected error in mat compiler3: "incorrect argument count in call (consumer 1 2)".
   misc.mo:Expected error in mat compiler3: "variable goto is not bound".
---- 3529,3548 ----
-  bytevector.mo:Expected error in mat bytevector->uint-list: "bytevector->uint-list: bytevector length 12 is not a multiple of size 10".
-  bytevector.mo:Expected error in mat bytevector->uint-list: "bytevector->uint-list: bytevector length 12 is not a multiple of size 11".
-  bytevector.mo:Expected error in mat bytevector->uint-list: "bytevector->uint-list: bytevector length 12 is not a multiple of size 50".
-! bytevector.mo:Expected error in mat bytevector=?: "incorrect number of arguments to #<procedure bytevector=?>".
-! bytevector.mo:Expected error in mat bytevector=?: "incorrect number of arguments to #<procedure bytevector=?>".
-! bytevector.mo:Expected error in mat bytevector=?: "incorrect number of arguments to #<procedure bytevector=?>".
-  bytevector.mo:Expected error in mat bytevector=?: "bytevector=?: a is not a bytevector".
-  bytevector.mo:Expected error in mat bytevector=?: "bytevector=?: "a" is not a bytevector".
-  bytevector.mo:Expected error in mat tspl/csug-examples: "invalid endianness "spam"".
+--- 3575,3586 ----
+  bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-truncate!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
   misc.mo:Expected error in mat compiler1: "variable i-am-not-bound is not bound".
   misc.mo:Expected error in mat compiler1: "attempt to apply non-procedure oops".
 ! misc.mo:Expected error in mat compiler1: "incorrect argument count in call (g (($top-level-value (...))))".
@@ -3723,7 +3738,7 @@
   misc.mo:Expected error in mat compiler3: "incorrect argument count in call (consumer 1 2)".
   misc.mo:Expected error in mat compiler3: "variable goto is not bound".
 ***************
-*** 3614,3634 ****
+*** 3652,3672 ****
   misc.mo:Expected error in mat cpletrec: "attempt to reference undefined variable b".
   misc.mo:Expected error in mat cpletrec: "attempt to assign undefined variable b".
   misc.mo:Expected error in mat compile-profile: "compile-profile: invalid mode src [must be #f, #t, source, or block]".
@@ -3745,7 +3760,7 @@
   misc.mo:Expected error in mat compile-profile: "profile-dump-data: #t is not a string".
   misc.mo:Expected error in mat compile-profile: "profile-dump-data: invalid dump 17".
   misc.mo:Expected error in mat compile-profile: "profile-dump-data: invalid dump (17)".
---- 3614,3634 ----
+--- 3652,3672 ----
   misc.mo:Expected error in mat cpletrec: "attempt to reference undefined variable b".
   misc.mo:Expected error in mat cpletrec: "attempt to assign undefined variable b".
   misc.mo:Expected error in mat compile-profile: "compile-profile: invalid mode src [must be #f, #t, source, or block]".
@@ -3768,7 +3783,7 @@
   misc.mo:Expected error in mat compile-profile: "profile-dump-data: invalid dump 17".
   misc.mo:Expected error in mat compile-profile: "profile-dump-data: invalid dump (17)".
 ***************
-*** 3661,3667 ****
+*** 3699,3705 ****
   misc.mo:Expected error in mat $fasl-file-equal?: "$fasl-file-equal?: failed for probably-does-not-exist: no such file or directory".
   misc.mo:Expected error in mat $fasl-file-equal?: "$fasl-file-equal?: failed for probably-does-not-exist: no such file or directory".
   misc.mo:Expected error in mat $fasl-file-equal?: "$fasl-file-equal?: record comparison failed while comparing testfile-fatfib1.so and testfile-fatfib3.so within fasl entry 2".
@@ -3776,7 +3791,7 @@
   misc.mo:Expected error in mat cost-center: "with-cost-center: foo is not a cost center".
   misc.mo:Expected error in mat cost-center: "with-cost-center: bar is not a procedure".
   misc.mo:Expected error in mat cost-center: "cost-center-instruction-count: 5 is not a cost center".
---- 3661,3667 ----
+--- 3699,3705 ----
   misc.mo:Expected error in mat $fasl-file-equal?: "$fasl-file-equal?: failed for probably-does-not-exist: no such file or directory".
   misc.mo:Expected error in mat $fasl-file-equal?: "$fasl-file-equal?: failed for probably-does-not-exist: no such file or directory".
   misc.mo:Expected error in mat $fasl-file-equal?: "$fasl-file-equal?: record comparison failed while comparing testfile-fatfib1.so and testfile-fatfib3.so within fasl entry 2".
@@ -3785,7 +3800,7 @@
   misc.mo:Expected error in mat cost-center: "with-cost-center: bar is not a procedure".
   misc.mo:Expected error in mat cost-center: "cost-center-instruction-count: 5 is not a cost center".
 ***************
-*** 3715,3722 ****
+*** 3753,3760 ****
   misc.mo:Expected error in mat apropos: "apropos: 3 is not a symbol or string".
   misc.mo:Expected error in mat apropos: "apropos: (hit me) is not a symbol or string".
   misc.mo:Expected error in mat apropos: "apropos-list: b is not an environment".
@@ -3794,7 +3809,7 @@
   misc.mo:Expected error in mat apropos: "variable $apropos-unbound1 is not bound".
   misc.mo:Expected error in mat apropos: "variable $apropos-unbound2 is not bound".
   misc.mo:Expected error in mat simplify-if: "textual-port?: a is not a port".
---- 3715,3722 ----
+--- 3753,3760 ----
   misc.mo:Expected error in mat apropos: "apropos: 3 is not a symbol or string".
   misc.mo:Expected error in mat apropos: "apropos: (hit me) is not a symbol or string".
   misc.mo:Expected error in mat apropos: "apropos-list: b is not an environment".
@@ -3804,7 +3819,7 @@
   misc.mo:Expected error in mat apropos: "variable $apropos-unbound2 is not bound".
   misc.mo:Expected error in mat simplify-if: "textual-port?: a is not a port".
 ***************
-*** 3741,3749 ****
+*** 3780,3788 ****
   cp0.mo:Expected error in mat cp0-regression: "source-object-efp: #f is not a source object".
   cp0.mo:Expected error in mat cp0-regression: "source-object-sfd: #f is not a source object".
   cp0.mo:Expected error in mat cp0-regression: "condition: #f is not a condition".
@@ -3814,7 +3829,7 @@
   cp0.mo:Expected error in mat expand-output: "expand-output: #t is not a textual output port or #f".
   cp0.mo:Expected error in mat expand-output: "expand-output: #<binary output port bytevector> is not a textual output port or #f".
   cp0.mo:Expected error in mat expand/optimize-output: "expand/optimize-output: #t is not a textual output port or #f".
---- 3741,3749 ----
+--- 3780,3788 ----
   cp0.mo:Expected error in mat cp0-regression: "source-object-efp: #f is not a source object".
   cp0.mo:Expected error in mat cp0-regression: "source-object-sfd: #f is not a source object".
   cp0.mo:Expected error in mat cp0-regression: "condition: #f is not a condition".
@@ -3825,7 +3840,7 @@
   cp0.mo:Expected error in mat expand-output: "expand-output: #<binary output port bytevector> is not a textual output port or #f".
   cp0.mo:Expected error in mat expand/optimize-output: "expand/optimize-output: #t is not a textual output port or #f".
 ***************
-*** 3807,3815 ****
+*** 3846,3854 ****
   5_6.mo:Expected error in mat list->fxvector: "list->fxvector: (1 2 . 3) is not a proper list".
   5_6.mo:Expected error in mat list->fxvector: "list->fxvector: (1 2 3 2 3 2 ...) is circular".
   5_6.mo:Expected error in mat fxvector->list: "fxvector->list: (a b c) is not an fxvector".
@@ -3835,7 +3850,7 @@
   5_6.mo:Expected error in mat vector-map: "vector-map: #() is not a procedure".
   5_6.mo:Expected error in mat vector-map: "vector-map: #() is not a procedure".
   5_6.mo:Expected error in mat vector-map: "vector-map: #() is not a procedure".
---- 3807,3815 ----
+--- 3846,3854 ----
   5_6.mo:Expected error in mat list->fxvector: "list->fxvector: (1 2 . 3) is not a proper list".
   5_6.mo:Expected error in mat list->fxvector: "list->fxvector: (1 2 3 2 3 2 ...) is circular".
   5_6.mo:Expected error in mat fxvector->list: "fxvector->list: (a b c) is not an fxvector".
@@ -3846,7 +3861,7 @@
   5_6.mo:Expected error in mat vector-map: "vector-map: #() is not a procedure".
   5_6.mo:Expected error in mat vector-map: "vector-map: #() is not a procedure".
 ***************
-*** 3824,3832 ****
+*** 3863,3871 ****
   5_6.mo:Expected error in mat vector-map: "vector-map: lengths of input vectors #() and #(x) differ".
   5_6.mo:Expected error in mat vector-map: "vector-map: lengths of input vectors #(y) and #() differ".
   5_6.mo:Expected error in mat vector-map: "vector-map: lengths of input vectors #(y) and #() differ".
@@ -3856,7 +3871,7 @@
   5_6.mo:Expected error in mat vector-for-each: "vector-for-each: #() is not a procedure".
   5_6.mo:Expected error in mat vector-for-each: "vector-for-each: #() is not a procedure".
   5_6.mo:Expected error in mat vector-for-each: "vector-for-each: #() is not a procedure".
---- 3824,3832 ----
+--- 3863,3871 ----
   5_6.mo:Expected error in mat vector-map: "vector-map: lengths of input vectors #() and #(x) differ".
   5_6.mo:Expected error in mat vector-map: "vector-map: lengths of input vectors #(y) and #() differ".
   5_6.mo:Expected error in mat vector-map: "vector-map: lengths of input vectors #(y) and #() differ".
@@ -3867,7 +3882,7 @@
   5_6.mo:Expected error in mat vector-for-each: "vector-for-each: #() is not a procedure".
   5_6.mo:Expected error in mat vector-for-each: "vector-for-each: #() is not a procedure".
 ***************
-*** 3841,3858 ****
+*** 3880,3897 ****
   5_6.mo:Expected error in mat vector-for-each: "vector-for-each: lengths of input vectors #() and #(x) differ".
   5_6.mo:Expected error in mat vector-for-each: "vector-for-each: lengths of input vectors #(y) and #() differ".
   5_6.mo:Expected error in mat vector-for-each: "vector-for-each: lengths of input vectors #(y) and #() differ".
@@ -3883,10 +3898,10 @@
 ! 5_6.mo:Expected error in mat vector-sort!: "incorrect argument count in call (vector-sort! >)".
 ! 5_6.mo:Expected error in mat vector-sort!: "incorrect argument count in call (vector-sort! (quote #(a b c)))".
 ! 5_6.mo:Expected error in mat vector-sort!: "incorrect argument count in call (vector-sort! > (quote #(1 2 3)) #t)".
-  5_6.mo:Expected error in mat vector-sort!: "vector-sort!: 3 is not a vector".
-  5_6.mo:Expected error in mat vector-sort!: "vector-sort!: (1 2 3) is not a vector".
+  5_6.mo:Expected error in mat vector-sort!: "vector-sort!: 3 is not a mutable vector".
+  5_6.mo:Expected error in mat vector-sort!: "vector-sort!: (1 2 3) is not a mutable vector".
   5_6.mo:Expected error in mat vector-sort!: "vector-sort!: #(a b c) is not a procedure".
---- 3841,3858 ----
+--- 3880,3897 ----
   5_6.mo:Expected error in mat vector-for-each: "vector-for-each: lengths of input vectors #() and #(x) differ".
   5_6.mo:Expected error in mat vector-for-each: "vector-for-each: lengths of input vectors #(y) and #() differ".
   5_6.mo:Expected error in mat vector-for-each: "vector-for-each: lengths of input vectors #(y) and #() differ".
@@ -3902,11 +3917,11 @@
 ! 5_6.mo:Expected error in mat vector-sort!: "incorrect number of arguments to #<procedure vector-sort!>".
 ! 5_6.mo:Expected error in mat vector-sort!: "incorrect number of arguments to #<procedure vector-sort!>".
 ! 5_6.mo:Expected error in mat vector-sort!: "incorrect number of arguments to #<procedure vector-sort!>".
-  5_6.mo:Expected error in mat vector-sort!: "vector-sort!: 3 is not a vector".
-  5_6.mo:Expected error in mat vector-sort!: "vector-sort!: (1 2 3) is not a vector".
+  5_6.mo:Expected error in mat vector-sort!: "vector-sort!: 3 is not a mutable vector".
+  5_6.mo:Expected error in mat vector-sort!: "vector-sort!: (1 2 3) is not a mutable vector".
   5_6.mo:Expected error in mat vector-sort!: "vector-sort!: #(a b c) is not a procedure".
 ***************
-*** 3914,3935 ****
+*** 3959,3980 ****
   6.mo:Expected error in mat port-operations: "clear-output-port: not permitted on closed port #<output port testfile.ss>".
   6.mo:Expected error in mat port-operations: "current-output-port: a is not a textual output port".
   6.mo:Expected error in mat port-operations: "current-input-port: a is not a textual input port".
@@ -3929,7 +3944,7 @@
   6.mo:Expected error in mat port-operations1: "open-input-output-file: furball is not a string".
   6.mo:Expected error in mat port-operations1: "open-input-output-file: failed for /probably/not/a/good/path: no such file or directory".
   6.mo:Expected error in mat port-operations1: "open-input-output-file: invalid option compressed".
---- 3914,3935 ----
+--- 3959,3980 ----
   6.mo:Expected error in mat port-operations: "clear-output-port: not permitted on closed port #<output port testfile.ss>".
   6.mo:Expected error in mat port-operations: "current-output-port: a is not a textual output port".
   6.mo:Expected error in mat port-operations: "current-input-port: a is not a textual input port".
@@ -3953,7 +3968,7 @@
   6.mo:Expected error in mat port-operations1: "open-input-output-file: failed for /probably/not/a/good/path: no such file or directory".
   6.mo:Expected error in mat port-operations1: "open-input-output-file: invalid option compressed".
 ***************
-*** 3938,3944 ****
+*** 3983,3989 ****
   6.mo:Expected error in mat port-operations1: "truncate-file: all-the-way is not a valid length".
   6.mo:Expected error in mat port-operations1: "truncate-file: #<input port testfile.ss> is not an output port".
   6.mo:Expected error in mat port-operations1: "truncate-file: animal-crackers is not an output port".
@@ -3961,7 +3976,7 @@
   6.mo:Expected error in mat port-operations1: "truncate-file: not permitted on closed port #<input/output port testfile.ss>".
   6.mo:Expected error in mat port-operations1: "get-output-string: #<input port string> is not a string output port".
   6.mo:Expected error in mat port-operations1: "get-output-string: #<output port testfile.ss> is not a string output port".
---- 3938,3944 ----
+--- 3983,3989 ----
   6.mo:Expected error in mat port-operations1: "truncate-file: all-the-way is not a valid length".
   6.mo:Expected error in mat port-operations1: "truncate-file: #<input port testfile.ss> is not an output port".
   6.mo:Expected error in mat port-operations1: "truncate-file: animal-crackers is not an output port".
@@ -3970,7 +3985,7 @@
   6.mo:Expected error in mat port-operations1: "get-output-string: #<input port string> is not a string output port".
   6.mo:Expected error in mat port-operations1: "get-output-string: #<output port testfile.ss> is not a string output port".
 ***************
-*** 3955,3962 ****
+*** 4000,4007 ****
   6.mo:Expected error in mat string-port-file-position: "file-position: -1 is not a valid position".
   6.mo:Expected error in mat fresh-line: "fresh-line: 3 is not a textual output port".
   6.mo:Expected error in mat fresh-line: "fresh-line: #<input port string> is not a textual output port".
@@ -3979,7 +3994,7 @@
   6.mo:Expected error in mat pretty-print: "pretty-format: 3 is not a symbol".
   6.mo:Expected error in mat pretty-print: "pretty-format: invalid format (bad 0 ... ... 0 format)".
   6.mo:Expected warning in mat cp1in-verify-format-warnings: "compile: too few arguments for control string "~a~~~s" in call to format".
---- 3955,3962 ----
+--- 4000,4007 ----
   6.mo:Expected error in mat string-port-file-position: "file-position: -1 is not a valid position".
   6.mo:Expected error in mat fresh-line: "fresh-line: 3 is not a textual output port".
   6.mo:Expected error in mat fresh-line: "fresh-line: #<input port string> is not a textual output port".
@@ -3989,7 +4004,7 @@
   6.mo:Expected error in mat pretty-print: "pretty-format: invalid format (bad 0 ... ... 0 format)".
   6.mo:Expected warning in mat cp1in-verify-format-warnings: "compile: too few arguments for control string "~a~~~s" in call to format".
 ***************
-*** 6440,6471 ****
+*** 6485,6516 ****
   io.mo:Expected error in mat port-operations: "put-u8: not permitted on closed port #<binary output port testfile.ss>".
   io.mo:Expected error in mat port-operations: "put-bytevector: not permitted on closed port #<binary output port testfile.ss>".
   io.mo:Expected error in mat port-operations: "flush-output-port: not permitted on closed port #<binary output port testfile.ss>".
@@ -4022,7 +4037,7 @@
   io.mo:Expected error in mat port-operations1: "open-file-input/output-port: failed for /probably/not/a/good/path: no such file or directory".
   io.mo:Expected error in mat port-operations1: "invalid file option uncompressed".
   io.mo:Expected error in mat port-operations1: "invalid file option truncate".
---- 6440,6471 ----
+--- 6485,6516 ----
   io.mo:Expected error in mat port-operations: "put-u8: not permitted on closed port #<binary output port testfile.ss>".
   io.mo:Expected error in mat port-operations: "put-bytevector: not permitted on closed port #<binary output port testfile.ss>".
   io.mo:Expected error in mat port-operations: "flush-output-port: not permitted on closed port #<binary output port testfile.ss>".
@@ -4056,7 +4071,7 @@
   io.mo:Expected error in mat port-operations1: "invalid file option uncompressed".
   io.mo:Expected error in mat port-operations1: "invalid file option truncate".
 ***************
-*** 6476,6482 ****
+*** 6521,6527 ****
   io.mo:Expected error in mat port-operations1: "set-port-length!: all-the-way is not a valid length".
   io.mo:Expected error in mat port-operations1: "truncate-port: #<binary input port testfile.ss> is not an output port".
   io.mo:Expected error in mat port-operations1: "truncate-port: animal-crackers is not an output port".
@@ -4064,7 +4079,7 @@
   io.mo:Expected error in mat port-operations1: "truncate-port: not permitted on closed port #<binary input/output port testfile.ss>".
   io.mo:Expected error in mat port-operations3: "file-port?: "not a port" is not a port".
   io.mo:Expected error in mat port-operations3: "port-file-descriptor: oops is not a port".
---- 6476,6482 ----
+--- 6521,6527 ----
   io.mo:Expected error in mat port-operations1: "set-port-length!: all-the-way is not a valid length".
   io.mo:Expected error in mat port-operations1: "truncate-port: #<binary input port testfile.ss> is not an output port".
   io.mo:Expected error in mat port-operations1: "truncate-port: animal-crackers is not an output port".
@@ -4073,7 +4088,7 @@
   io.mo:Expected error in mat port-operations3: "file-port?: "not a port" is not a port".
   io.mo:Expected error in mat port-operations3: "port-file-descriptor: oops is not a port".
 ***************
-*** 6659,6671 ****
+*** 6704,6716 ****
   io.mo:Expected error in mat low-level-port-operations: "set-binary-port-output-size!: #vu8(1 2 3) is not a valid size for #<binary output port bytevector>".
   io.mo:Expected error in mat low-level-port-operations: "set-binary-port-output-size!: -1 is not a valid size for #<binary output port bytevector>".
   io.mo:Expected error in mat low-level-port-operations: "set-binary-port-output-size!: 6 is not a valid size for #<binary output port bytevector>".
@@ -4087,7 +4102,7 @@
   io.mo:Expected error in mat custom-port-buffer-size: "custom-port-buffer-size: shoe is not a positive fixnum".
   io.mo:Expected error in mat custom-port-buffer-size: "custom-port-buffer-size: 0 is not a positive fixnum".
   io.mo:Expected error in mat custom-port-buffer-size: "custom-port-buffer-size: -15 is not a positive fixnum".
---- 6659,6671 ----
+--- 6704,6716 ----
   io.mo:Expected error in mat low-level-port-operations: "set-binary-port-output-size!: #vu8(1 2 3) is not a valid size for #<binary output port bytevector>".
   io.mo:Expected error in mat low-level-port-operations: "set-binary-port-output-size!: -1 is not a valid size for #<binary output port bytevector>".
   io.mo:Expected error in mat low-level-port-operations: "set-binary-port-output-size!: 6 is not a valid size for #<binary output port bytevector>".
@@ -4102,7 +4117,7 @@
   io.mo:Expected error in mat custom-port-buffer-size: "custom-port-buffer-size: 0 is not a positive fixnum".
   io.mo:Expected error in mat custom-port-buffer-size: "custom-port-buffer-size: -15 is not a positive fixnum".
 ***************
-*** 6673,6688 ****
+*** 6718,6733 ****
   io.mo:Expected error in mat custom-port-buffer-size: "custom-port-buffer-size: 1024.0 is not a positive fixnum".
   io.mo:Expected error in mat compression: "port-file-compressed!: #<output port string> is not a file port".
   io.mo:Expected error in mat compression: "port-file-compressed!: cannot compress input/output port #<binary input/output port testfile.ss>".
@@ -4119,7 +4134,7 @@
   io.mo:Expected error in mat custom-binary-ports: "unget-u8: cannot unget 255 on #<binary input port foo>".
   io.mo:Expected error in mat custom-binary-ports: "put-u8: #<binary input port foo> is not a binary output port".
   io.mo:Expected error in mat custom-binary-ports: "port-length: #<binary input port foo> does not support operation".
---- 6673,6688 ----
+--- 6718,6733 ----
   io.mo:Expected error in mat custom-port-buffer-size: "custom-port-buffer-size: 1024.0 is not a positive fixnum".
   io.mo:Expected error in mat compression: "port-file-compressed!: #<output port string> is not a file port".
   io.mo:Expected error in mat compression: "port-file-compressed!: cannot compress input/output port #<binary input/output port testfile.ss>".
@@ -4137,7 +4152,7 @@
   io.mo:Expected error in mat custom-binary-ports: "put-u8: #<binary input port foo> is not a binary output port".
   io.mo:Expected error in mat custom-binary-ports: "port-length: #<binary input port foo> does not support operation".
 ***************
-*** 6754,6769 ****
+*** 6799,6814 ****
   io.mo:Expected error in mat current-ports: "console-output-port: #<input port string> is not a textual output port".
   io.mo:Expected error in mat current-ports: "console-error-port: #<input port string> is not a textual output port".
   io.mo:Expected error in mat current-transcoder: "current-transcoder: #<output port string> is not a transcoder".
@@ -4154,7 +4169,7 @@
   io.mo:Expected error in mat utf-16-codec: "utf-16-codec: invalid endianness #f".
   io.mo:Expected error in mat to-fold-or-not-to-fold: "get-datum: invalid character name #\newLine at char 0 of #<input port string>".
   io.mo:Expected error in mat to-fold-or-not-to-fold: "get-datum: invalid character name #\newLine at char 15 of #<input port string>".
---- 6754,6769 ----
+--- 6799,6814 ----
   io.mo:Expected error in mat current-ports: "console-output-port: #<input port string> is not a textual output port".
   io.mo:Expected error in mat current-ports: "console-error-port: #<input port string> is not a textual output port".
   io.mo:Expected error in mat current-transcoder: "current-transcoder: #<output port string> is not a transcoder".
@@ -4172,7 +4187,7 @@
   io.mo:Expected error in mat to-fold-or-not-to-fold: "get-datum: invalid character name #\newLine at char 0 of #<input port string>".
   io.mo:Expected error in mat to-fold-or-not-to-fold: "get-datum: invalid character name #\newLine at char 15 of #<input port string>".
 ***************
-*** 6934,6940 ****
+*** 6979,6985 ****
   7.mo:Expected error in mat eval-when: "invalid syntax visit-x".
   7.mo:Expected error in mat eval-when: "invalid syntax revisit-x".
   7.mo:Expected error in mat compile-whole-program: "compile-whole-program: failed for nosuchfile.wpo: no such file or directory".
@@ -4180,7 +4195,7 @@
   7.mo:Expected error in mat compile-whole-program: "separate-eval: Exception: library (testfile-wpo-a4) not found
   7.mo:Expected error in mat compile-whole-program: "separate-eval: Exception: library (testfile-wpo-c4) not found
   7.mo:Expected error in mat compile-whole-program: "separate-eval: Exception: attempt to invoke library (testfile-wpo-c5) while it is still being loaded
---- 6934,6940 ----
+--- 6979,6985 ----
   7.mo:Expected error in mat eval-when: "invalid syntax visit-x".
   7.mo:Expected error in mat eval-when: "invalid syntax revisit-x".
   7.mo:Expected error in mat compile-whole-program: "compile-whole-program: failed for nosuchfile.wpo: no such file or directory".
@@ -4189,7 +4204,7 @@
   7.mo:Expected error in mat compile-whole-program: "separate-eval: Exception: library (testfile-wpo-c4) not found
   7.mo:Expected error in mat compile-whole-program: "separate-eval: Exception: attempt to invoke library (testfile-wpo-c5) while it is still being loaded
 ***************
-*** 6948,6974 ****
+*** 6993,7019 ****
   7.mo:Expected error in mat compile-whole-library: "separate-eval: Exception: library (testfile-cwl-c6) not found
   7.mo:Expected error in mat compile-whole-library: "separate-compile: Exception in compile-whole-library: encountered visit-only run-time library (testfile-cwl-a9) while processing file "testfile-cwl-a9.wpo"
   7.mo:Expected error in mat top-level-value-functions: "top-level-bound?: "hello" is not a symbol".
@@ -4217,7 +4232,7 @@
   7.mo:Expected error in mat top-level-value-functions: "define-top-level-value: hello is not an environment".
   7.mo:Expected error in mat top-level-value-functions: "define-top-level-value: #<environment *scheme*> is not a symbol".
   7.mo:Expected error in mat top-level-value-functions: "variable i-am-not-bound-i-hope is not bound".
---- 6948,6974 ----
+--- 6993,7019 ----
   7.mo:Expected error in mat compile-whole-library: "separate-eval: Exception: library (testfile-cwl-c6) not found
   7.mo:Expected error in mat compile-whole-library: "separate-compile: Exception in compile-whole-library: encountered visit-only run-time library (testfile-cwl-a9) while processing file "testfile-cwl-a9.wpo"
   7.mo:Expected error in mat top-level-value-functions: "top-level-bound?: "hello" is not a symbol".
@@ -4246,7 +4261,7 @@
   7.mo:Expected error in mat top-level-value-functions: "define-top-level-value: #<environment *scheme*> is not a symbol".
   7.mo:Expected error in mat top-level-value-functions: "variable i-am-not-bound-i-hope is not bound".
 ***************
-*** 7356,7446 ****
+*** 7401,7491 ****
   hash.mo:Expected error in mat old-hash-table: "hash-table-for-each: ((a . b)) is not an eq hashtable".
   hash.mo:Expected error in mat old-hash-table: "incorrect number of arguments to #<procedure>".
   hash.mo:Expected error in mat old-hash-table: "incorrect number of arguments to #<procedure>".
@@ -4338,7 +4353,7 @@
   hash.mo:Expected error in mat hashtable-arguments: "hashtable-weak?: (hash . table) is not a hashtable".
   hash.mo:Expected error in mat hash-return-value: "hashtable-ref: invalid hash-function #<procedure> return value "oops" for any".
   hash.mo:Expected error in mat hash-return-value: "hashtable-ref: invalid hash-function #<procedure> return value 3.5 for any".
---- 7356,7446 ----
+--- 7401,7491 ----
   hash.mo:Expected error in mat old-hash-table: "hash-table-for-each: ((a . b)) is not an eq hashtable".
   hash.mo:Expected error in mat old-hash-table: "incorrect number of arguments to #<procedure>".
   hash.mo:Expected error in mat old-hash-table: "incorrect number of arguments to #<procedure>".
@@ -4431,7 +4446,7 @@
   hash.mo:Expected error in mat hash-return-value: "hashtable-ref: invalid hash-function #<procedure> return value "oops" for any".
   hash.mo:Expected error in mat hash-return-value: "hashtable-ref: invalid hash-function #<procedure> return value 3.5 for any".
 ***************
-*** 7460,7555 ****
+*** 7505,7600 ****
   hash.mo:Expected error in mat hash-return-value: "hashtable-delete!: invalid hash-function #<procedure> return value "oops" for any".
   hash.mo:Expected error in mat hash-return-value: "hashtable-delete!: invalid hash-function #<procedure> return value 3.5 for any".
   hash.mo:Expected error in mat hash-return-value: "hashtable-delete!: invalid hash-function #<procedure> return value 1+2i for any".
@@ -4528,7 +4543,7 @@
   hash.mo:Expected error in mat eqv-hashtable-arguments: "make-weak-eqv-hashtable: invalid size argument -1".
   hash.mo:Expected error in mat eqv-hashtable-arguments: "make-weak-eqv-hashtable: invalid size argument #t".
   hash.mo:Expected error in mat eqv-hashtable-arguments: "make-weak-eqv-hashtable: invalid size argument #f".
---- 7460,7555 ----
+--- 7505,7600 ----
   hash.mo:Expected error in mat hash-return-value: "hashtable-delete!: invalid hash-function #<procedure> return value "oops" for any".
   hash.mo:Expected error in mat hash-return-value: "hashtable-delete!: invalid hash-function #<procedure> return value 3.5 for any".
   hash.mo:Expected error in mat hash-return-value: "hashtable-delete!: invalid hash-function #<procedure> return value 1+2i for any".
@@ -4626,7 +4641,7 @@
   hash.mo:Expected error in mat eqv-hashtable-arguments: "make-weak-eqv-hashtable: invalid size argument #t".
   hash.mo:Expected error in mat eqv-hashtable-arguments: "make-weak-eqv-hashtable: invalid size argument #f".
 ***************
-*** 7557,7572 ****
+*** 7602,7617 ****
   hash.mo:Expected error in mat generic-hashtable: "hashtable-delete!: #<hashtable> is not mutable".
   hash.mo:Expected error in mat generic-hashtable: "hashtable-update!: #<hashtable> is not mutable".
   hash.mo:Expected error in mat generic-hashtable: "hashtable-update!: #<hashtable> is not mutable".
@@ -4643,7 +4658,7 @@
   hash.mo:Expected error in mat hash-functions: "string-ci-hash: hello is not a string".
   hash.mo:Expected error in mat fasl-other-hashtable: "fasl-write: invalid fasl object #<eqv hashtable>".
   hash.mo:Expected error in mat fasl-other-hashtable: "fasl-write: invalid fasl object #<hashtable>".
---- 7557,7572 ----
+--- 7602,7617 ----
   hash.mo:Expected error in mat generic-hashtable: "hashtable-delete!: #<hashtable> is not mutable".
   hash.mo:Expected error in mat generic-hashtable: "hashtable-update!: #<hashtable> is not mutable".
   hash.mo:Expected error in mat generic-hashtable: "hashtable-update!: #<hashtable> is not mutable".
@@ -4661,7 +4676,7 @@
   hash.mo:Expected error in mat fasl-other-hashtable: "fasl-write: invalid fasl object #<eqv hashtable>".
   hash.mo:Expected error in mat fasl-other-hashtable: "fasl-write: invalid fasl object #<hashtable>".
 ***************
-*** 7681,7688 ****
+*** 7726,7733 ****
   8.mo:Expected error in mat with-syntax: "invalid syntax a".
   8.mo:Expected error in mat with-syntax: "duplicate pattern variable x in (x x)".
   8.mo:Expected error in mat with-syntax: "duplicate pattern variable x in (x x)".
@@ -4670,7 +4685,7 @@
   8.mo:Expected error in mat generate-temporaries: "generate-temporaries: improper list structure (a b . c)".
   8.mo:Expected error in mat generate-temporaries: "generate-temporaries: cyclic list structure (a b c b c b ...)".
   8.mo:Expected error in mat syntax->list: "syntax->list: invalid argument #<syntax a>".
---- 7681,7688 ----
+--- 7726,7733 ----
   8.mo:Expected error in mat with-syntax: "invalid syntax a".
   8.mo:Expected error in mat with-syntax: "duplicate pattern variable x in (x x)".
   8.mo:Expected error in mat with-syntax: "duplicate pattern variable x in (x x)".
@@ -4680,7 +4695,7 @@
   8.mo:Expected error in mat generate-temporaries: "generate-temporaries: cyclic list structure (a b c b c b ...)".
   8.mo:Expected error in mat syntax->list: "syntax->list: invalid argument #<syntax a>".
 ***************
-*** 8270,8285 ****
+*** 8315,8330 ****
   8.mo:Expected error in mat rnrs-eval: "attempt to assign unbound identifier foo".
   8.mo:Expected error in mat rnrs-eval: "invalid definition in immutable environment (define cons (quote #<procedure vector>))".
   8.mo:Expected error in mat top-level-syntax-functions: "top-level-syntax: "hello" is not a symbol".
@@ -4697,7 +4712,7 @@
   8.mo:Expected error in mat top-level-syntax-functions: "define-top-level-syntax: hello is not an environment".
   8.mo:Expected error in mat top-level-syntax-functions: "define-top-level-syntax: #<environment *scheme*> is not a symbol".
   8.mo:Expected error in mat top-level-syntax-functions: "define-top-level-syntax: cannot modify immutable environment #<environment *scheme*>".
---- 8270,8285 ----
+--- 8315,8330 ----
   8.mo:Expected error in mat rnrs-eval: "attempt to assign unbound identifier foo".
   8.mo:Expected error in mat rnrs-eval: "invalid definition in immutable environment (define cons (quote #<procedure vector>))".
   8.mo:Expected error in mat top-level-syntax-functions: "top-level-syntax: "hello" is not a symbol".
@@ -4715,7 +4730,7 @@
   8.mo:Expected error in mat top-level-syntax-functions: "define-top-level-syntax: #<environment *scheme*> is not a symbol".
   8.mo:Expected error in mat top-level-syntax-functions: "define-top-level-syntax: cannot modify immutable environment #<environment *scheme*>".
 ***************
-*** 8358,8380 ****
+*** 8403,8425 ****
   fx.mo:Expected error in mat fx=?: "fx=?: (a) is not a fixnum".
   fx.mo:Expected error in mat fx=?: "fx=?: <int> is not a fixnum".
   fx.mo:Expected error in mat fx=?: "fx=?: <-int> is not a fixnum".
@@ -4739,7 +4754,7 @@
   fx.mo:Expected error in mat $fxu<: "incorrect number of arguments to #<procedure $fxu<>".
   fx.mo:Expected error in mat $fxu<: "incorrect number of arguments to #<procedure $fxu<>".
   fx.mo:Expected error in mat $fxu<: "$fxu<: <-int> is not a fixnum".
---- 8358,8380 ----
+--- 8403,8425 ----
   fx.mo:Expected error in mat fx=?: "fx=?: (a) is not a fixnum".
   fx.mo:Expected error in mat fx=?: "fx=?: <int> is not a fixnum".
   fx.mo:Expected error in mat fx=?: "fx=?: <-int> is not a fixnum".
@@ -4764,7 +4779,7 @@
   fx.mo:Expected error in mat $fxu<: "incorrect number of arguments to #<procedure $fxu<>".
   fx.mo:Expected error in mat $fxu<: "$fxu<: <-int> is not a fixnum".
 ***************
-*** 8406,8418 ****
+*** 8451,8463 ****
   fx.mo:Expected error in mat r6rs:fx-: "fx-: #f is not a fixnum".
   fx.mo:Expected error in mat r6rs:fx-: "fx-: #f is not a fixnum".
   fx.mo:Expected error in mat fx*: "fx*: (a . b) is not a fixnum".
@@ -4778,7 +4793,7 @@
   fx.mo:Expected error in mat r6rs:fx*: "fx*: <int> is not a fixnum".
   fx.mo:Expected error in mat r6rs:fx*: "fx*: <-int> is not a fixnum".
   fx.mo:Expected error in mat r6rs:fx*: "fx*: #f is not a fixnum".
---- 8406,8418 ----
+--- 8451,8463 ----
   fx.mo:Expected error in mat r6rs:fx-: "fx-: #f is not a fixnum".
   fx.mo:Expected error in mat r6rs:fx-: "fx-: #f is not a fixnum".
   fx.mo:Expected error in mat fx*: "fx*: (a . b) is not a fixnum".
@@ -4793,7 +4808,7 @@
   fx.mo:Expected error in mat r6rs:fx*: "fx*: <-int> is not a fixnum".
   fx.mo:Expected error in mat r6rs:fx*: "fx*: #f is not a fixnum".
 ***************
-*** 8462,8474 ****
+*** 8507,8519 ****
   fx.mo:Expected error in mat fx1+: "fx1+: <-int> is not a fixnum".
   fx.mo:Expected error in mat fx1+: "fx1+: <int> is not a fixnum".
   fx.mo:Expected error in mat fx1+: "fx1+: a is not a fixnum".
@@ -4807,7 +4822,7 @@
   fx.mo:Expected error in mat fxmax: "fxmax: a is not a fixnum".
   fx.mo:Expected error in mat fxmax: "fxmax: <int> is not a fixnum".
   fx.mo:Expected error in mat fxmax: "fxmax: <-int> is not a fixnum".
---- 8462,8474 ----
+--- 8507,8519 ----
   fx.mo:Expected error in mat fx1+: "fx1+: <-int> is not a fixnum".
   fx.mo:Expected error in mat fx1+: "fx1+: <int> is not a fixnum".
   fx.mo:Expected error in mat fx1+: "fx1+: a is not a fixnum".
@@ -4822,7 +4837,7 @@
   fx.mo:Expected error in mat fxmax: "fxmax: <int> is not a fixnum".
   fx.mo:Expected error in mat fxmax: "fxmax: <-int> is not a fixnum".
 ***************
-*** 8565,8574 ****
+*** 8610,8619 ****
   fx.mo:Expected error in mat fxarithmetic-shift: "fxarithmetic-shift: fixnum overflow with arguments <int> and 10".
   fx.mo:Expected error in mat fxarithmetic-shift: "fxarithmetic-shift: fixnum overflow with arguments 4096 and <int>".
   fx.mo:Expected error in mat fxarithmetic-shift: "fxarithmetic-shift: fixnum overflow with arguments <-int> and 1".
@@ -4833,7 +4848,7 @@
   fx.mo:Expected error in mat fxbit-field: "fxbit-field: 35.0 is not a fixnum".
   fx.mo:Expected error in mat fxbit-field: "fxbit-field: 5.0 is not a valid start index".
   fx.mo:Expected error in mat fxbit-field: "fxbit-field: 8.0 is not a valid end index".
---- 8565,8574 ----
+--- 8610,8619 ----
   fx.mo:Expected error in mat fxarithmetic-shift: "fxarithmetic-shift: fixnum overflow with arguments <int> and 10".
   fx.mo:Expected error in mat fxarithmetic-shift: "fxarithmetic-shift: fixnum overflow with arguments 4096 and <int>".
   fx.mo:Expected error in mat fxarithmetic-shift: "fxarithmetic-shift: fixnum overflow with arguments <-int> and 1".
@@ -4845,7 +4860,7 @@
   fx.mo:Expected error in mat fxbit-field: "fxbit-field: 5.0 is not a valid start index".
   fx.mo:Expected error in mat fxbit-field: "fxbit-field: 8.0 is not a valid end index".
 ***************
-*** 8582,8615 ****
+*** 8627,8660 ****
   fx.mo:Expected error in mat fxbit-field: "fxbit-field: <int> is not a valid end index".
   fx.mo:Expected error in mat fxbit-field: "fxbit-field: <int> is not a valid start index".
   fx.mo:Expected error in mat fxbit-field: "fxbit-field: <int> is not a valid end index".
@@ -4880,7 +4895,7 @@
   fx.mo:Expected error in mat fxif: "fxif: a is not a fixnum".
   fx.mo:Expected error in mat fxif: "fxif: 3.4 is not a fixnum".
   fx.mo:Expected error in mat fxif: "fxif: (a) is not a fixnum".
---- 8582,8615 ----
+--- 8627,8660 ----
   fx.mo:Expected error in mat fxbit-field: "fxbit-field: <int> is not a valid end index".
   fx.mo:Expected error in mat fxbit-field: "fxbit-field: <int> is not a valid start index".
   fx.mo:Expected error in mat fxbit-field: "fxbit-field: <int> is not a valid end index".
@@ -4916,7 +4931,7 @@
   fx.mo:Expected error in mat fxif: "fxif: 3.4 is not a fixnum".
   fx.mo:Expected error in mat fxif: "fxif: (a) is not a fixnum".
 ***************
-*** 8619,8662 ****
+*** 8664,8707 ****
   fx.mo:Expected error in mat fxif: "fxif: <-int> is not a fixnum".
   fx.mo:Expected error in mat fxif: "fxif: <-int> is not a fixnum".
   fx.mo:Expected error in mat fxif: "fxif: <-int> is not a fixnum".
@@ -4961,7 +4976,7 @@
   fx.mo:Expected error in mat fxcopy-bit: "fxcopy-bit: 3.4 is not a fixnum".
   fx.mo:Expected error in mat fxcopy-bit: "fxcopy-bit: "3" is not a fixnum".
   fx.mo:Expected error in mat fxcopy-bit: "fxcopy-bit: <int> is not a fixnum".
---- 8619,8662 ----
+--- 8664,8707 ----
   fx.mo:Expected error in mat fxif: "fxif: <-int> is not a fixnum".
   fx.mo:Expected error in mat fxif: "fxif: <-int> is not a fixnum".
   fx.mo:Expected error in mat fxif: "fxif: <-int> is not a fixnum".
@@ -5007,7 +5022,7 @@
   fx.mo:Expected error in mat fxcopy-bit: "fxcopy-bit: "3" is not a fixnum".
   fx.mo:Expected error in mat fxcopy-bit: "fxcopy-bit: <int> is not a fixnum".
 ***************
-*** 8665,8675 ****
+*** 8710,8720 ****
   fx.mo:Expected error in mat fxcopy-bit: "fxcopy-bit: invalid bit index -1".
   fx.mo:Expected error in mat fxcopy-bit: "fxcopy-bit: invalid bit index <int>".
   fx.mo:Expected error in mat fxcopy-bit: "fxcopy-bit: invalid bit index <int>".
@@ -5019,7 +5034,7 @@
   fx.mo:Expected error in mat fxcopy-bit-field: "fxcopy-bit-field: "3" is not a fixnum".
   fx.mo:Expected error in mat fxcopy-bit-field: "fxcopy-bit-field: 3.4 is not a valid start index".
   fx.mo:Expected error in mat fxcopy-bit-field: "fxcopy-bit-field: 3/4 is not a valid end index".
---- 8665,8675 ----
+--- 8710,8720 ----
   fx.mo:Expected error in mat fxcopy-bit: "fxcopy-bit: invalid bit index -1".
   fx.mo:Expected error in mat fxcopy-bit: "fxcopy-bit: invalid bit index <int>".
   fx.mo:Expected error in mat fxcopy-bit: "fxcopy-bit: invalid bit index <int>".
@@ -5032,7 +5047,7 @@
   fx.mo:Expected error in mat fxcopy-bit-field: "fxcopy-bit-field: 3.4 is not a valid start index".
   fx.mo:Expected error in mat fxcopy-bit-field: "fxcopy-bit-field: 3/4 is not a valid end index".
 ***************
-*** 8729,8738 ****
+*** 8774,8783 ****
   fx.mo:Expected error in mat fxdiv0-and-mod0: "fxmod0: (a) is not a fixnum".
   fx.mo:Expected error in mat fxdiv0-and-mod0: "fxmod0: undefined for 0".
   fx.mo:Expected error in mat fxdiv0-and-mod0: "fxmod0: undefined for 0".
@@ -5043,7 +5058,7 @@
   fx.mo:Expected error in mat fx+/carry: "fx+/carry: 1.0 is not a fixnum".
   fx.mo:Expected error in mat fx+/carry: "fx+/carry: 2.0 is not a fixnum".
   fx.mo:Expected error in mat fx+/carry: "fx+/carry: 3.0 is not a fixnum".
---- 8729,8738 ----
+--- 8774,8783 ----
   fx.mo:Expected error in mat fxdiv0-and-mod0: "fxmod0: (a) is not a fixnum".
   fx.mo:Expected error in mat fxdiv0-and-mod0: "fxmod0: undefined for 0".
   fx.mo:Expected error in mat fxdiv0-and-mod0: "fxmod0: undefined for 0".
@@ -5055,7 +5070,7 @@
   fx.mo:Expected error in mat fx+/carry: "fx+/carry: 2.0 is not a fixnum".
   fx.mo:Expected error in mat fx+/carry: "fx+/carry: 3.0 is not a fixnum".
 ***************
-*** 8748,8757 ****
+*** 8793,8802 ****
   fx.mo:Expected error in mat fx+/carry: "fx+/carry: <-int> is not a fixnum".
   fx.mo:Expected error in mat fx+/carry: "fx+/carry: <-int> is not a fixnum".
   fx.mo:Expected error in mat fx+/carry: "fx+/carry: <-int> is not a fixnum".
@@ -5066,7 +5081,7 @@
   fx.mo:Expected error in mat fx-/carry: "fx-/carry: 1.0 is not a fixnum".
   fx.mo:Expected error in mat fx-/carry: "fx-/carry: 2.0 is not a fixnum".
   fx.mo:Expected error in mat fx-/carry: "fx-/carry: 3.0 is not a fixnum".
---- 8748,8757 ----
+--- 8793,8802 ----
   fx.mo:Expected error in mat fx+/carry: "fx+/carry: <-int> is not a fixnum".
   fx.mo:Expected error in mat fx+/carry: "fx+/carry: <-int> is not a fixnum".
   fx.mo:Expected error in mat fx+/carry: "fx+/carry: <-int> is not a fixnum".
@@ -5078,7 +5093,7 @@
   fx.mo:Expected error in mat fx-/carry: "fx-/carry: 2.0 is not a fixnum".
   fx.mo:Expected error in mat fx-/carry: "fx-/carry: 3.0 is not a fixnum".
 ***************
-*** 8767,8776 ****
+*** 8812,8821 ****
   fx.mo:Expected error in mat fx-/carry: "fx-/carry: <-int> is not a fixnum".
   fx.mo:Expected error in mat fx-/carry: "fx-/carry: <-int> is not a fixnum".
   fx.mo:Expected error in mat fx-/carry: "fx-/carry: <-int> is not a fixnum".
@@ -5089,7 +5104,7 @@
   fx.mo:Expected error in mat fx*/carry: "fx*/carry: 1.0 is not a fixnum".
   fx.mo:Expected error in mat fx*/carry: "fx*/carry: 2.0 is not a fixnum".
   fx.mo:Expected error in mat fx*/carry: "fx*/carry: 3.0 is not a fixnum".
---- 8767,8776 ----
+--- 8812,8821 ----
   fx.mo:Expected error in mat fx-/carry: "fx-/carry: <-int> is not a fixnum".
   fx.mo:Expected error in mat fx-/carry: "fx-/carry: <-int> is not a fixnum".
   fx.mo:Expected error in mat fx-/carry: "fx-/carry: <-int> is not a fixnum".
@@ -5101,7 +5116,7 @@
   fx.mo:Expected error in mat fx*/carry: "fx*/carry: 2.0 is not a fixnum".
   fx.mo:Expected error in mat fx*/carry: "fx*/carry: 3.0 is not a fixnum".
 ***************
-*** 8786,8796 ****
+*** 8831,8841 ****
   fx.mo:Expected error in mat fx*/carry: "fx*/carry: <-int> is not a fixnum".
   fx.mo:Expected error in mat fx*/carry: "fx*/carry: <-int> is not a fixnum".
   fx.mo:Expected error in mat fx*/carry: "fx*/carry: <-int> is not a fixnum".
@@ -5113,7 +5128,7 @@
   fx.mo:Expected error in mat fxrotate-bit-field: "fxrotate-bit-field: a is not a fixnum".
   fx.mo:Expected error in mat fxrotate-bit-field: "fxrotate-bit-field: invalid start index 0.0".
   fx.mo:Expected error in mat fxrotate-bit-field: "fxrotate-bit-field: invalid end index 2.0".
---- 8786,8796 ----
+--- 8831,8841 ----
   fx.mo:Expected error in mat fx*/carry: "fx*/carry: <-int> is not a fixnum".
   fx.mo:Expected error in mat fx*/carry: "fx*/carry: <-int> is not a fixnum".
   fx.mo:Expected error in mat fx*/carry: "fx*/carry: <-int> is not a fixnum".
@@ -5126,7 +5141,7 @@
   fx.mo:Expected error in mat fxrotate-bit-field: "fxrotate-bit-field: invalid start index 0.0".
   fx.mo:Expected error in mat fxrotate-bit-field: "fxrotate-bit-field: invalid end index 2.0".
 ***************
-*** 8813,8822 ****
+*** 8858,8867 ****
   fx.mo:Expected error in mat fxrotate-bit-field: "fxrotate-bit-field: invalid end index <int>".
   fx.mo:Expected error in mat fxrotate-bit-field: "fxrotate-bit-field: invalid end index <int>".
   fx.mo:Expected error in mat fxrotate-bit-field: "fxrotate-bit-field: count 1 is greater than difference between end index 5 and start index 5".
@@ -5137,7 +5152,7 @@
   fx.mo:Expected error in mat fxreverse-bit-field: "fxreverse-bit-field: a is not a fixnum".
   fx.mo:Expected error in mat fxreverse-bit-field: "fxreverse-bit-field: invalid start index 0.0".
   fx.mo:Expected error in mat fxreverse-bit-field: "fxreverse-bit-field: invalid end index 2.0".
---- 8813,8822 ----
+--- 8858,8867 ----
   fx.mo:Expected error in mat fxrotate-bit-field: "fxrotate-bit-field: invalid end index <int>".
   fx.mo:Expected error in mat fxrotate-bit-field: "fxrotate-bit-field: invalid end index <int>".
   fx.mo:Expected error in mat fxrotate-bit-field: "fxrotate-bit-field: count 1 is greater than difference between end index 5 and start index 5".
@@ -5149,7 +5164,7 @@
   fx.mo:Expected error in mat fxreverse-bit-field: "fxreverse-bit-field: invalid start index 0.0".
   fx.mo:Expected error in mat fxreverse-bit-field: "fxreverse-bit-field: invalid end index 2.0".
 ***************
-*** 8832,8849 ****
+*** 8877,8894 ****
   fx.mo:Expected error in mat fxreverse-bit-field: "fxreverse-bit-field: invalid end index <int>".
   fx.mo:Expected error in mat fxreverse-bit-field: "fxreverse-bit-field: invalid end index <-int>".
   fx.mo:Expected error in mat fxreverse-bit-field: "fxreverse-bit-field: start index 7 is greater than end index 5".
@@ -5168,7 +5183,7 @@
   fl.mo:Expected error in mat fl=: "fl=: (a) is not a flonum".
   fl.mo:Expected error in mat fl=: "fl=: a is not a flonum".
   fl.mo:Expected error in mat fl=: "fl=: a is not a flonum".
---- 8832,8849 ----
+--- 8877,8894 ----
   fx.mo:Expected error in mat fxreverse-bit-field: "fxreverse-bit-field: invalid end index <int>".
   fx.mo:Expected error in mat fxreverse-bit-field: "fxreverse-bit-field: invalid end index <-int>".
   fx.mo:Expected error in mat fxreverse-bit-field: "fxreverse-bit-field: start index 7 is greater than end index 5".
@@ -5188,7 +5203,7 @@
   fl.mo:Expected error in mat fl=: "fl=: a is not a flonum".
   fl.mo:Expected error in mat fl=: "fl=: a is not a flonum".
 ***************
-*** 8851,8857 ****
+*** 8896,8902 ****
   fl.mo:Expected error in mat fl=: "fl=: 3 is not a flonum".
   fl.mo:Expected error in mat fl=: "fl=: 7/2 is not a flonum".
   fl.mo:Expected error in mat fl=: "fl=: 7/2 is not a flonum".
@@ -5196,7 +5211,7 @@
   fl.mo:Expected error in mat fl<: "fl<: (a) is not a flonum".
   fl.mo:Expected error in mat fl<: "fl<: a is not a flonum".
   fl.mo:Expected error in mat fl<: "fl<: a is not a flonum".
---- 8851,8857 ----
+--- 8896,8902 ----
   fl.mo:Expected error in mat fl=: "fl=: 3 is not a flonum".
   fl.mo:Expected error in mat fl=: "fl=: 7/2 is not a flonum".
   fl.mo:Expected error in mat fl=: "fl=: 7/2 is not a flonum".
@@ -5205,7 +5220,7 @@
   fl.mo:Expected error in mat fl<: "fl<: a is not a flonum".
   fl.mo:Expected error in mat fl<: "fl<: a is not a flonum".
 ***************
-*** 8859,8865 ****
+*** 8904,8910 ****
   fl.mo:Expected error in mat fl<: "fl<: 3 is not a flonum".
   fl.mo:Expected error in mat fl<: "fl<: 7/2 is not a flonum".
   fl.mo:Expected error in mat fl<: "fl<: 7/2 is not a flonum".
@@ -5213,7 +5228,7 @@
   fl.mo:Expected error in mat fl>: "fl>: (a) is not a flonum".
   fl.mo:Expected error in mat fl>: "fl>: a is not a flonum".
   fl.mo:Expected error in mat fl>: "fl>: a is not a flonum".
---- 8859,8865 ----
+--- 8904,8910 ----
   fl.mo:Expected error in mat fl<: "fl<: 3 is not a flonum".
   fl.mo:Expected error in mat fl<: "fl<: 7/2 is not a flonum".
   fl.mo:Expected error in mat fl<: "fl<: 7/2 is not a flonum".
@@ -5222,7 +5237,7 @@
   fl.mo:Expected error in mat fl>: "fl>: a is not a flonum".
   fl.mo:Expected error in mat fl>: "fl>: a is not a flonum".
 ***************
-*** 8867,8873 ****
+*** 8912,8918 ****
   fl.mo:Expected error in mat fl>: "fl>: 3 is not a flonum".
   fl.mo:Expected error in mat fl>: "fl>: 7/2 is not a flonum".
   fl.mo:Expected error in mat fl>: "fl>: 7/2 is not a flonum".
@@ -5230,7 +5245,7 @@
   fl.mo:Expected error in mat fl<=: "fl<=: (a) is not a flonum".
   fl.mo:Expected error in mat fl<=: "fl<=: a is not a flonum".
   fl.mo:Expected error in mat fl<=: "fl<=: a is not a flonum".
---- 8867,8873 ----
+--- 8912,8918 ----
   fl.mo:Expected error in mat fl>: "fl>: 3 is not a flonum".
   fl.mo:Expected error in mat fl>: "fl>: 7/2 is not a flonum".
   fl.mo:Expected error in mat fl>: "fl>: 7/2 is not a flonum".
@@ -5239,7 +5254,7 @@
   fl.mo:Expected error in mat fl<=: "fl<=: a is not a flonum".
   fl.mo:Expected error in mat fl<=: "fl<=: a is not a flonum".
 ***************
-*** 8875,8881 ****
+*** 8920,8926 ****
   fl.mo:Expected error in mat fl<=: "fl<=: 3 is not a flonum".
   fl.mo:Expected error in mat fl<=: "fl<=: 7/2 is not a flonum".
   fl.mo:Expected error in mat fl<=: "fl<=: 7/2 is not a flonum".
@@ -5247,7 +5262,7 @@
   fl.mo:Expected error in mat fl>=: "fl>=: (a) is not a flonum".
   fl.mo:Expected error in mat fl>=: "fl>=: a is not a flonum".
   fl.mo:Expected error in mat fl>=: "fl>=: a is not a flonum".
---- 8875,8881 ----
+--- 8920,8926 ----
   fl.mo:Expected error in mat fl<=: "fl<=: 3 is not a flonum".
   fl.mo:Expected error in mat fl<=: "fl<=: 7/2 is not a flonum".
   fl.mo:Expected error in mat fl<=: "fl<=: 7/2 is not a flonum".
@@ -5256,7 +5271,7 @@
   fl.mo:Expected error in mat fl>=: "fl>=: a is not a flonum".
   fl.mo:Expected error in mat fl>=: "fl>=: a is not a flonum".
 ***************
-*** 8883,8922 ****
+*** 8928,8967 ****
   fl.mo:Expected error in mat fl>=: "fl>=: 3 is not a flonum".
   fl.mo:Expected error in mat fl>=: "fl>=: 7/2 is not a flonum".
   fl.mo:Expected error in mat fl>=: "fl>=: 7/2 is not a flonum".
@@ -5297,7 +5312,7 @@
   fl.mo:Expected error in mat fl>=?: "fl>=?: a is not a flonum".
   fl.mo:Expected error in mat fl>=?: "fl>=?: a is not a flonum".
   fl.mo:Expected error in mat fl>=?: "fl>=?: 3 is not a flonum".
---- 8883,8922 ----
+--- 8928,8967 ----
   fl.mo:Expected error in mat fl>=: "fl>=: 3 is not a flonum".
   fl.mo:Expected error in mat fl>=: "fl>=: 7/2 is not a flonum".
   fl.mo:Expected error in mat fl>=: "fl>=: 7/2 is not a flonum".
@@ -5339,7 +5354,7 @@
   fl.mo:Expected error in mat fl>=?: "fl>=?: a is not a flonum".
   fl.mo:Expected error in mat fl>=?: "fl>=?: 3 is not a flonum".
 ***************
-*** 8926,8932 ****
+*** 8971,8977 ****
   fl.mo:Expected error in mat fl+: "fl+: (a . b) is not a flonum".
   fl.mo:Expected error in mat fl+: "fl+: 1 is not a flonum".
   fl.mo:Expected error in mat fl+: "fl+: 2/3 is not a flonum".
@@ -5347,7 +5362,7 @@
   fl.mo:Expected error in mat fl-: "fl-: (a . b) is not a flonum".
   fl.mo:Expected error in mat fl-: "fl-: 1 is not a flonum".
   fl.mo:Expected error in mat fl-: "fl-: a is not a flonum".
---- 8926,8932 ----
+--- 8971,8977 ----
   fl.mo:Expected error in mat fl+: "fl+: (a . b) is not a flonum".
   fl.mo:Expected error in mat fl+: "fl+: 1 is not a flonum".
   fl.mo:Expected error in mat fl+: "fl+: 2/3 is not a flonum".
@@ -5356,7 +5371,7 @@
   fl.mo:Expected error in mat fl-: "fl-: 1 is not a flonum".
   fl.mo:Expected error in mat fl-: "fl-: a is not a flonum".
 ***************
-*** 8936,9018 ****
+*** 8981,9063 ****
   fl.mo:Expected error in mat fl*: "fl*: (a . b) is not a flonum".
   fl.mo:Expected error in mat fl*: "fl*: 1 is not a flonum".
   fl.mo:Expected error in mat fl*: "fl*: 2/3 is not a flonum".
@@ -5440,7 +5455,7 @@
   fl.mo:Expected error in mat flround: "flround: a is not a flonum".
   fl.mo:Expected error in mat flround: "flround: 2.0+1.0i is not a flonum".
   fl.mo:Expected error in mat flround: "flround: 2+1i is not a flonum".
---- 8936,9018 ----
+--- 8981,9063 ----
   fl.mo:Expected error in mat fl*: "fl*: (a . b) is not a flonum".
   fl.mo:Expected error in mat fl*: "fl*: 1 is not a flonum".
   fl.mo:Expected error in mat fl*: "fl*: 2/3 is not a flonum".
@@ -5525,7 +5540,7 @@
   fl.mo:Expected error in mat flround: "flround: 2.0+1.0i is not a flonum".
   fl.mo:Expected error in mat flround: "flround: 2+1i is not a flonum".
 ***************
-*** 9032,9080 ****
+*** 9077,9125 ****
   fl.mo:Expected error in mat flinfinite?: "flinfinite?: 3 is not a flonum".
   fl.mo:Expected error in mat flinfinite?: "flinfinite?: 3/4 is not a flonum".
   fl.mo:Expected error in mat flinfinite?: "flinfinite?: hi is not a flonum".
@@ -5575,7 +5590,7 @@
   fl.mo:Expected error in mat flmin: "flmin: a is not a flonum".
   fl.mo:Expected error in mat flmin: "flmin: a is not a flonum".
   fl.mo:Expected error in mat flmin: "flmin: a is not a flonum".
---- 9032,9080 ----
+--- 9077,9125 ----
   fl.mo:Expected error in mat flinfinite?: "flinfinite?: 3 is not a flonum".
   fl.mo:Expected error in mat flinfinite?: "flinfinite?: 3/4 is not a flonum".
   fl.mo:Expected error in mat flinfinite?: "flinfinite?: hi is not a flonum".
@@ -5626,7 +5641,7 @@
   fl.mo:Expected error in mat flmin: "flmin: a is not a flonum".
   fl.mo:Expected error in mat flmin: "flmin: a is not a flonum".
 ***************
-*** 9082,9088 ****
+*** 9127,9133 ****
   fl.mo:Expected error in mat flmin: "flmin: a is not a flonum".
   fl.mo:Expected error in mat flmin: "flmin: 0.0+1.0i is not a flonum".
   fl.mo:Expected error in mat flmin: "flmin: 0+1i is not a flonum".
@@ -5634,7 +5649,7 @@
   fl.mo:Expected error in mat flmax: "flmax: a is not a flonum".
   fl.mo:Expected error in mat flmax: "flmax: a is not a flonum".
   fl.mo:Expected error in mat flmax: "flmax: 3 is not a flonum".
---- 9082,9088 ----
+--- 9127,9133 ----
   fl.mo:Expected error in mat flmin: "flmin: a is not a flonum".
   fl.mo:Expected error in mat flmin: "flmin: 0.0+1.0i is not a flonum".
   fl.mo:Expected error in mat flmin: "flmin: 0+1i is not a flonum".
@@ -5643,7 +5658,7 @@
   fl.mo:Expected error in mat flmax: "flmax: a is not a flonum".
   fl.mo:Expected error in mat flmax: "flmax: 3 is not a flonum".
 ***************
-*** 9090,9103 ****
+*** 9135,9148 ****
   fl.mo:Expected error in mat flmax: "flmax: a is not a flonum".
   fl.mo:Expected error in mat flmax: "flmax: 0.0+1.0i is not a flonum".
   fl.mo:Expected error in mat flmax: "flmax: 0+1i is not a flonum".
@@ -5658,7 +5673,7 @@
   fl.mo:Expected error in mat fldenominator: "fldenominator: a is not a flonum".
   fl.mo:Expected error in mat fldenominator: "fldenominator: 3 is not a flonum".
   fl.mo:Expected error in mat fldenominator: "fldenominator: 0+1i is not a flonum".
---- 9090,9103 ----
+--- 9135,9148 ----
   fl.mo:Expected error in mat flmax: "flmax: a is not a flonum".
   fl.mo:Expected error in mat flmax: "flmax: 0.0+1.0i is not a flonum".
   fl.mo:Expected error in mat flmax: "flmax: 0+1i is not a flonum".
@@ -5674,7 +5689,7 @@
   fl.mo:Expected error in mat fldenominator: "fldenominator: 3 is not a flonum".
   fl.mo:Expected error in mat fldenominator: "fldenominator: 0+1i is not a flonum".
 ***************
-*** 9143,9149 ****
+*** 9188,9194 ****
   cfl.mo:Expected error in mat cfl-: "cfl-: a is not a cflonum".
   cfl.mo:Expected error in mat cfl-: "cfl-: a is not a cflonum".
   cfl.mo:Expected error in mat cfl-: "cfl-: a is not a cflonum".
@@ -5682,7 +5697,7 @@
   cfl.mo:Expected error in mat cfl-: "cfl-: a is not a cflonum".
   cfl.mo:Expected error in mat cfl-: "cfl-: a is not a cflonum".
   cfl.mo:Expected error in mat cfl-: "cfl-: a is not a cflonum".
---- 9143,9149 ----
+--- 9188,9194 ----
   cfl.mo:Expected error in mat cfl-: "cfl-: a is not a cflonum".
   cfl.mo:Expected error in mat cfl-: "cfl-: a is not a cflonum".
   cfl.mo:Expected error in mat cfl-: "cfl-: a is not a cflonum".
@@ -5691,7 +5706,7 @@
   cfl.mo:Expected error in mat cfl-: "cfl-: a is not a cflonum".
   cfl.mo:Expected error in mat cfl-: "cfl-: a is not a cflonum".
 ***************
-*** 9153,9166 ****
+*** 9198,9211 ****
   cfl.mo:Expected error in mat cfl/: "cfl/: a is not a cflonum".
   cfl.mo:Expected error in mat cfl/: "cfl/: a is not a cflonum".
   cfl.mo:Expected error in mat cfl/: "cfl/: a is not a cflonum".
@@ -5706,7 +5721,7 @@
   foreign.mo:Expected error in mat load-shared-object: "load-shared-object: invalid path 3".
   foreign.mo:Expected error in mat foreign-procedure: "foreign-procedure: no entry for "i do not exist"".
   foreign.mo:Expected error in mat foreign-procedure: "foreign-procedure: no entry for "i do not exist"".
---- 9153,9166 ----
+--- 9198,9211 ----
   cfl.mo:Expected error in mat cfl/: "cfl/: a is not a cflonum".
   cfl.mo:Expected error in mat cfl/: "cfl/: a is not a cflonum".
   cfl.mo:Expected error in mat cfl/: "cfl/: a is not a cflonum".
@@ -5722,7 +5737,7 @@
   foreign.mo:Expected error in mat foreign-procedure: "foreign-procedure: no entry for "i do not exist"".
   foreign.mo:Expected error in mat foreign-procedure: "foreign-procedure: no entry for "i do not exist"".
 ***************
-*** 9195,9202 ****
+*** 9240,9247 ****
   foreign.mo:Expected error in mat foreign-procedure: "id: invalid foreign-procedure argument foo".
   foreign.mo:Expected error in mat foreign-procedure: "foreign-procedure: invalid foreign procedure handle abcde".
   foreign.mo:Expected error in mat foreign-procedure: "float_id: invalid foreign-procedure argument 0".
@@ -5731,7 +5746,7 @@
   foreign.mo:Expected error in mat foreign-sizeof: "foreign-sizeof: invalid foreign type specifier i-am-not-a-type".
   foreign.mo:Expected error in mat foreign-sizeof: "foreign-sizeof: invalid foreign type specifier 1".
   foreign.mo:Expected error in mat foreign-bytevectors: "u8*->u8*: invalid foreign-procedure argument "hello"".
---- 9195,9202 ----
+--- 9240,9247 ----
   foreign.mo:Expected error in mat foreign-procedure: "id: invalid foreign-procedure argument foo".
   foreign.mo:Expected error in mat foreign-procedure: "foreign-procedure: invalid foreign procedure handle abcde".
   foreign.mo:Expected error in mat foreign-procedure: "float_id: invalid foreign-procedure argument 0".
@@ -5741,7 +5756,7 @@
   foreign.mo:Expected error in mat foreign-sizeof: "foreign-sizeof: invalid foreign type specifier 1".
   foreign.mo:Expected error in mat foreign-bytevectors: "u8*->u8*: invalid foreign-procedure argument "hello"".
 ***************
-*** 9680,9692 ****
+*** 9725,9737 ****
   unix.mo:Expected error in mat file-operations: "file-access-time: failed for "testlink": no such file or directory".
   unix.mo:Expected error in mat file-operations: "file-change-time: failed for "testlink": no such file or directory".
   unix.mo:Expected error in mat file-operations: "file-modification-time: failed for "testlink": no such file or directory".
@@ -5755,7 +5770,7 @@
   windows.mo:Expected error in mat registry: "get-registry: pooh is not a string".
   windows.mo:Expected error in mat registry: "put-registry!: 3 is not a string".
   windows.mo:Expected error in mat registry: "put-registry!: 3 is not a string".
---- 9680,9692 ----
+--- 9725,9737 ----
   unix.mo:Expected error in mat file-operations: "file-access-time: failed for "testlink": no such file or directory".
   unix.mo:Expected error in mat file-operations: "file-change-time: failed for "testlink": no such file or directory".
   unix.mo:Expected error in mat file-operations: "file-modification-time: failed for "testlink": no such file or directory".
@@ -5770,7 +5785,7 @@
   windows.mo:Expected error in mat registry: "put-registry!: 3 is not a string".
   windows.mo:Expected error in mat registry: "put-registry!: 3 is not a string".
 ***************
-*** 9714,9785 ****
+*** 9759,9830 ****
   ieee.mo:Expected error in mat flonum->fixnum: "flonum->fixnum: result for -inf.0 would be outside of fixnum range".
   ieee.mo:Expected error in mat flonum->fixnum: "flonum->fixnum: result for +nan.0 would be outside of fixnum range".
   ieee.mo:Expected error in mat fllp: "fllp: 3 is not a flonum".
@@ -5843,7 +5858,7 @@
   date.mo:Expected error in mat time: "time>=?: 3 is not a time record".
   date.mo:Expected error in mat time: "time>=?: #<procedure car> is not a time record".
   date.mo:Expected error in mat time: "time>=?: types of <time> and <time> differ".
---- 9714,9785 ----
+--- 9759,9830 ----
   ieee.mo:Expected error in mat flonum->fixnum: "flonum->fixnum: result for -inf.0 would be outside of fixnum range".
   ieee.mo:Expected error in mat flonum->fixnum: "flonum->fixnum: result for +nan.0 would be outside of fixnum range".
   ieee.mo:Expected error in mat fllp: "fllp: 3 is not a flonum".
@@ -5917,7 +5932,7 @@
   date.mo:Expected error in mat time: "time>=?: #<procedure car> is not a time record".
   date.mo:Expected error in mat time: "time>=?: types of <time> and <time> differ".
 ***************
-*** 9787,9801 ****
+*** 9832,9846 ****
   date.mo:Expected error in mat time: "add-duration: <time> does not have type time-duration".
   date.mo:Expected error in mat time: "subtract-duration: <time> does not have type time-duration".
   date.mo:Expected error in mat time: "copy-time: <date> is not a time record".
@@ -5933,7 +5948,7 @@
   date.mo:Expected error in mat date: "make-date: invalid nanosecond -1".
   date.mo:Expected error in mat date: "make-date: invalid nanosecond <int>".
   date.mo:Expected error in mat date: "make-date: invalid nanosecond zero".
---- 9787,9801 ----
+--- 9832,9846 ----
   date.mo:Expected error in mat time: "add-duration: <time> does not have type time-duration".
   date.mo:Expected error in mat time: "subtract-duration: <time> does not have type time-duration".
   date.mo:Expected error in mat time: "copy-time: <date> is not a time record".
@@ -5950,7 +5965,7 @@
   date.mo:Expected error in mat date: "make-date: invalid nanosecond <int>".
   date.mo:Expected error in mat date: "make-date: invalid nanosecond zero".
 ***************
-*** 9821,9873 ****
+*** 9866,9918 ****
   date.mo:Expected error in mat date: "make-date: invalid time-zone offset 90000".
   date.mo:Expected error in mat date: "make-date: invalid time-zone offset est".
   date.mo:Expected error in mat date: "make-date: invalid time-zone offset "est"".
@@ -6004,7 +6019,7 @@
   date.mo:Expected error in mat date: "current-date: invalid time-zone offset -90000".
   date.mo:Expected error in mat date: "current-date: invalid time-zone offset 90000".
   date.mo:Expected error in mat conversions/sleep: "date->time-utc: <time> is not a date record".
---- 9821,9873 ----
+--- 9866,9918 ----
   date.mo:Expected error in mat date: "make-date: invalid time-zone offset 90000".
   date.mo:Expected error in mat date: "make-date: invalid time-zone offset est".
   date.mo:Expected error in mat date: "make-date: invalid time-zone offset "est"".
diff --git a/mats/patch-interpret-0-f-f-f b/mats/patch-interpret-0-f-f-f
index dd51d11795..7e973fc2e1 100644
--- a/mats/patch-interpret-0-f-f-f
+++ b/mats/patch-interpret-0-f-f-f
@@ -1,5 +1,5 @@
-*** errors-compile-0-f-f-f	2016-05-01 13:38:30.812572752 -0400
---- errors-interpret-0-f-f-f	2016-05-01 13:27:13.120817742 -0400
+*** errors-compile-0-f-f-f	2017-03-15 00:21:57.000000000 -0400
+--- errors-interpret-0-f-f-f	2017-03-15 00:06:40.000000000 -0400
 ***************
 *** 1,7 ****
   primvars.mo:Expected error in mat make-parameter: "make-parameter: 2 is not a procedure".
@@ -196,7 +196,7 @@
   3.mo:Expected error in mat mrvs: "returned two values to single value return context".
   3.mo:Expected error in mat mrvs: "cdr: a is not a pair".
 ***************
-*** 3959,3974 ****
+*** 4004,4019 ****
   6.mo:Expected error in mat pretty-print: "incorrect argument count in call (pretty-format (quote foo) (quote x) (quote x))".
   6.mo:Expected error in mat pretty-print: "pretty-format: 3 is not a symbol".
   6.mo:Expected error in mat pretty-print: "pretty-format: invalid format (bad 0 ... ... 0 format)".
@@ -213,9 +213,9 @@
   6.mo:Expected warning in mat cp1in-verify-format-warnings: "compile: too few arguments for control string "abc~s" in call to fprintf at line 1, char 29 of testfile.ss".
   6.mo:Expected warning in mat cp1in-verify-format-warnings: "compile: too many arguments for control string "~%~abc~adef~ag~s~~~%" in call to fprintf at line 1, char 29 of testfile.ss".
   6.mo:Expected error in mat print-parameters: "write: cycle detected; proceeding with (print-graph #t)".
---- 3965,3974 ----
+--- 4010,4019 ----
 ***************
-*** 6914,6920 ****
+*** 6959,6965 ****
   7.mo:Expected error in mat maybe-compile: "separate-compile: Exception in include: failed for testfile-mc-1a.ss: no such file or directory
   7.mo:Expected error in mat maybe-compile: "separate-compile: Exception in maybe-compile-library: failed for "testfile-mc-1a.ss": no such file or directory
   7.mo:Expected error in mat maybe-compile: "separate-compile: Exception in maybe-compile-library: file "testfile-mc-1a.ss" not found in source directories
@@ -223,7 +223,7 @@
   7.mo:Expected error in mat eval: "interpret: 7 is not an environment".
   7.mo:Expected error in mat eval: "compile: 7 is not an environment".
   7.mo:Expected error in mat expand: "sc-expand: 7 is not an environment".
---- 6914,6920 ----
+--- 6959,6965 ----
   7.mo:Expected error in mat maybe-compile: "separate-compile: Exception in include: failed for testfile-mc-1a.ss: no such file or directory
   7.mo:Expected error in mat maybe-compile: "separate-compile: Exception in maybe-compile-library: failed for "testfile-mc-1a.ss": no such file or directory
   7.mo:Expected error in mat maybe-compile: "separate-compile: Exception in maybe-compile-library: file "testfile-mc-1a.ss" not found in source directories
@@ -232,7 +232,7 @@
   7.mo:Expected error in mat eval: "compile: 7 is not an environment".
   7.mo:Expected error in mat expand: "sc-expand: 7 is not an environment".
 ***************
-*** 7232,7238 ****
+*** 7277,7283 ****
   record.mo:Expected error in mat record25: "invalid value #\9 for foreign type uptr".
   record.mo:Expected error in mat record25: "invalid value 10 for foreign type float".
   record.mo:Expected error in mat record25: "invalid value 11.0+0.0i for foreign type double".
@@ -240,7 +240,7 @@
   record.mo:Expected error in mat record25: "invalid value 12.0 for foreign type long-long".
   record.mo:Expected error in mat record25: "invalid value 13.0 for foreign type unsigned-long-long".
   record.mo:Expected error in mat record25: "invalid value 3.0 for foreign type int".
---- 7232,7238 ----
+--- 7277,7283 ----
   record.mo:Expected error in mat record25: "invalid value #\9 for foreign type uptr".
   record.mo:Expected error in mat record25: "invalid value 10 for foreign type float".
   record.mo:Expected error in mat record25: "invalid value 11.0+0.0i for foreign type double".
@@ -249,7 +249,7 @@
   record.mo:Expected error in mat record25: "invalid value 13.0 for foreign type unsigned-long-long".
   record.mo:Expected error in mat record25: "invalid value 3.0 for foreign type int".
 ***************
-*** 8406,8418 ****
+*** 8451,8463 ****
   fx.mo:Expected error in mat r6rs:fx-: "fx-: #f is not a fixnum".
   fx.mo:Expected error in mat r6rs:fx-: "fx-: #f is not a fixnum".
   fx.mo:Expected error in mat fx*: "fx*: (a . b) is not a fixnum".
@@ -263,7 +263,7 @@
   fx.mo:Expected error in mat r6rs:fx*: "fx*: <int> is not a fixnum".
   fx.mo:Expected error in mat r6rs:fx*: "fx*: <-int> is not a fixnum".
   fx.mo:Expected error in mat r6rs:fx*: "fx*: #f is not a fixnum".
---- 8406,8418 ----
+--- 8451,8463 ----
   fx.mo:Expected error in mat r6rs:fx-: "fx-: #f is not a fixnum".
   fx.mo:Expected error in mat r6rs:fx-: "fx-: #f is not a fixnum".
   fx.mo:Expected error in mat fx*: "fx*: (a . b) is not a fixnum".
@@ -278,7 +278,7 @@
   fx.mo:Expected error in mat r6rs:fx*: "fx*: <-int> is not a fixnum".
   fx.mo:Expected error in mat r6rs:fx*: "fx*: #f is not a fixnum".
 ***************
-*** 9168,9192 ****
+*** 9213,9237 ****
   foreign.mo:Expected error in mat foreign-procedure: "foreign-procedure: invalid foreign procedure handle foo".
   foreign.mo:Expected error in mat foreign-procedure: "foreign-procedure: invalid foreign procedure handle foo".
   foreign.mo:Expected error in mat foreign-procedure: "foreign-procedure: invalid foreign procedure handle foo".
@@ -304,7 +304,7 @@
   foreign.mo:Expected error in mat foreign-procedure: "invalid foreign-procedure argument type specifier booleen".
   foreign.mo:Expected error in mat foreign-procedure: "invalid foreign-procedure argument type specifier integer-34".
   foreign.mo:Expected error in mat foreign-procedure: "invalid foreign-procedure result type specifier chare".
---- 9168,9192 ----
+--- 9213,9237 ----
   foreign.mo:Expected error in mat foreign-procedure: "foreign-procedure: invalid foreign procedure handle foo".
   foreign.mo:Expected error in mat foreign-procedure: "foreign-procedure: invalid foreign procedure handle foo".
   foreign.mo:Expected error in mat foreign-procedure: "foreign-procedure: invalid foreign procedure handle foo".
@@ -331,7 +331,7 @@
   foreign.mo:Expected error in mat foreign-procedure: "invalid foreign-procedure argument type specifier integer-34".
   foreign.mo:Expected error in mat foreign-procedure: "invalid foreign-procedure result type specifier chare".
 ***************
-*** 9199,9230 ****
+*** 9244,9275 ****
   foreign.mo:Expected error in mat foreign-sizeof: "incorrect argument count in call (foreign-sizeof (quote int) (quote int))".
   foreign.mo:Expected error in mat foreign-sizeof: "foreign-sizeof: invalid foreign type specifier i-am-not-a-type".
   foreign.mo:Expected error in mat foreign-sizeof: "foreign-sizeof: invalid foreign type specifier 1".
@@ -364,7 +364,7 @@
   foreign.mo:Expected error in mat foreign-strings: "foreign-callable: invalid return value ("ello" 4) from #<procedure>".
   foreign.mo:Expected error in mat foreign-strings: "foreign-callable: invalid return value ("ello" 4) from #<procedure>".
   foreign.mo:Expected error in mat foreign-strings: "foreign-callable: invalid return value ("ello" 4) from #<procedure>".
---- 9199,9230 ----
+--- 9244,9275 ----
   foreign.mo:Expected error in mat foreign-sizeof: "incorrect argument count in call (foreign-sizeof (quote int) (quote int))".
   foreign.mo:Expected error in mat foreign-sizeof: "foreign-sizeof: invalid foreign type specifier i-am-not-a-type".
   foreign.mo:Expected error in mat foreign-sizeof: "foreign-sizeof: invalid foreign type specifier 1".
@@ -398,7 +398,7 @@
   foreign.mo:Expected error in mat foreign-strings: "foreign-callable: invalid return value ("ello" 4) from #<procedure>".
   foreign.mo:Expected error in mat foreign-strings: "foreign-callable: invalid return value ("ello" 4) from #<procedure>".
 ***************
-*** 9232,9257 ****
+*** 9277,9302 ****
   foreign.mo:Expected error in mat foreign-strings: "foreign-callable: invalid return value ("ello" 4) from #<procedure>".
   foreign.mo:Expected error in mat foreign-strings: "foreign-callable: invalid return value ("ello" 4) from #<procedure>".
   foreign.mo:Expected error in mat foreign-strings: "foreign-callable: invalid return value ("ello" 4) from #<procedure>".
@@ -425,7 +425,7 @@
   foreign.mo:Expected error in mat foreign-fixed-types: "foreign-callable: invalid return value (- x 7) from #<procedure>".
   foreign.mo:Expected error in mat foreign-fixed-types: "foreign-callable: invalid return value (- x 7) from #<procedure>".
   foreign.mo:Expected error in mat foreign-fixed-types: "foreign-callable: invalid return value (- x 7) from #<procedure>".
---- 9232,9257 ----
+--- 9277,9302 ----
   foreign.mo:Expected error in mat foreign-strings: "foreign-callable: invalid return value ("ello" 4) from #<procedure>".
   foreign.mo:Expected error in mat foreign-strings: "foreign-callable: invalid return value ("ello" 4) from #<procedure>".
   foreign.mo:Expected error in mat foreign-strings: "foreign-callable: invalid return value ("ello" 4) from #<procedure>".
@@ -453,7 +453,7 @@
   foreign.mo:Expected error in mat foreign-fixed-types: "foreign-callable: invalid return value (- x 7) from #<procedure>".
   foreign.mo:Expected error in mat foreign-fixed-types: "foreign-callable: invalid return value (- x 7) from #<procedure>".
 ***************
-*** 9262,9296 ****
+*** 9307,9341 ****
   foreign.mo:Expected error in mat foreign-fixed-types: "foreign-callable: invalid return value (- x 7) from #<procedure>".
   foreign.mo:Expected error in mat foreign-fixed-types: "foreign-callable: invalid return value (- x 7) from #<procedure>".
   foreign.mo:Expected error in mat foreign-fixed-types: "foreign-callable: invalid return value (- x 7) from #<procedure>".
@@ -489,7 +489,7 @@
   foreign.mo:Expected error in mat foreign-C-types: "foreign-callable: invalid return value (73 74) from #<procedure>".
   foreign.mo:Expected error in mat foreign-C-types: "foreign-callable: invalid return value (73 74) from #<procedure>".
   foreign.mo:Expected error in mat foreign-C-types: "foreign-callable: invalid return value (73 74) from #<procedure>".
---- 9262,9296 ----
+--- 9307,9341 ----
   foreign.mo:Expected error in mat foreign-fixed-types: "foreign-callable: invalid return value (- x 7) from #<procedure>".
   foreign.mo:Expected error in mat foreign-fixed-types: "foreign-callable: invalid return value (- x 7) from #<procedure>".
   foreign.mo:Expected error in mat foreign-fixed-types: "foreign-callable: invalid return value (- x 7) from #<procedure>".
@@ -526,7 +526,7 @@
   foreign.mo:Expected error in mat foreign-C-types: "foreign-callable: invalid return value (73 74) from #<procedure>".
   foreign.mo:Expected error in mat foreign-C-types: "foreign-callable: invalid return value (73 74) from #<procedure>".
 ***************
-*** 9876,9885 ****
+*** 9921,9930 ****
   exceptions.mo:Expected error in mat assert: "failed assertion (memq (quote b) (quote (1 2 a 3 4)))".
   exceptions.mo:Expected error in mat assert: "failed assertion (q ...)".
   exceptions.mo:Expected error in mat assert: "failed assertion (andmap symbol? (syntax (x ...)))".
@@ -537,7 +537,7 @@
   oop.mo:Expected error in mat oop: "m1: not applicable to 17".
   oop.mo:Expected error in mat oop: "variable <a>-x1 is not bound".
   oop.mo:Expected error in mat oop: "variable <a>-x1-set! is not bound".
---- 9876,9885 ----
+--- 9921,9930 ----
   exceptions.mo:Expected error in mat assert: "failed assertion (memq (quote b) (quote (1 2 a 3 4)))".
   exceptions.mo:Expected error in mat assert: "failed assertion (q ...)".
   exceptions.mo:Expected error in mat assert: "failed assertion (andmap symbol? (syntax (x ...)))".
diff --git a/mats/patch-interpret-0-f-t-f b/mats/patch-interpret-0-f-t-f
index aded2fcd0e..05407d0156 100644
--- a/mats/patch-interpret-0-f-t-f
+++ b/mats/patch-interpret-0-f-t-f
@@ -1,5 +1,5 @@
-*** errors-compile-0-f-t-f	2016-05-01 13:17:27.556633016 -0400
---- errors-interpret-0-f-t-f	2016-05-01 13:32:19.876348905 -0400
+*** errors-compile-0-f-t-f	2017-03-14 23:53:20.000000000 -0400
+--- errors-interpret-0-f-t-f	2017-03-15 00:13:47.000000000 -0400
 ***************
 *** 1,7 ****
   primvars.mo:Expected error in mat make-parameter: "make-parameter: 2 is not a procedure".
@@ -169,7 +169,7 @@
   3.mo:Expected error in mat letrec: "variable f is not bound".
   3.mo:Expected error in mat letrec: "attempt to reference undefined variable a".
 ***************
-*** 3959,3974 ****
+*** 4004,4019 ****
   6.mo:Expected error in mat pretty-print: "incorrect argument count in call (pretty-format (quote foo) (quote x) (quote x))".
   6.mo:Expected error in mat pretty-print: "pretty-format: 3 is not a symbol".
   6.mo:Expected error in mat pretty-print: "pretty-format: invalid format (bad 0 ... ... 0 format)".
@@ -186,9 +186,9 @@
   6.mo:Expected warning in mat cp1in-verify-format-warnings: "compile: too few arguments for control string "abc~s" in call to fprintf at line 1, char 29 of testfile.ss".
   6.mo:Expected warning in mat cp1in-verify-format-warnings: "compile: too many arguments for control string "~%~abc~adef~ag~s~~~%" in call to fprintf at line 1, char 29 of testfile.ss".
   6.mo:Expected error in mat print-parameters: "write: cycle detected; proceeding with (print-graph #t)".
---- 3965,3974 ----
+--- 4010,4019 ----
 ***************
-*** 6914,6920 ****
+*** 6959,6965 ****
   7.mo:Expected error in mat maybe-compile: "separate-compile: Exception in include: failed for testfile-mc-1a.ss: no such file or directory
   7.mo:Expected error in mat maybe-compile: "separate-compile: Exception in maybe-compile-library: failed for "testfile-mc-1a.ss": no such file or directory
   7.mo:Expected error in mat maybe-compile: "separate-compile: Exception in maybe-compile-library: file "testfile-mc-1a.ss" not found in source directories
@@ -196,7 +196,7 @@
   7.mo:Expected error in mat eval: "interpret: 7 is not an environment".
   7.mo:Expected error in mat eval: "compile: 7 is not an environment".
   7.mo:Expected error in mat expand: "sc-expand: 7 is not an environment".
---- 6914,6920 ----
+--- 6959,6965 ----
   7.mo:Expected error in mat maybe-compile: "separate-compile: Exception in include: failed for testfile-mc-1a.ss: no such file or directory
   7.mo:Expected error in mat maybe-compile: "separate-compile: Exception in maybe-compile-library: failed for "testfile-mc-1a.ss": no such file or directory
   7.mo:Expected error in mat maybe-compile: "separate-compile: Exception in maybe-compile-library: file "testfile-mc-1a.ss" not found in source directories
@@ -205,7 +205,7 @@
   7.mo:Expected error in mat eval: "compile: 7 is not an environment".
   7.mo:Expected error in mat expand: "sc-expand: 7 is not an environment".
 ***************
-*** 7050,7057 ****
+*** 7095,7102 ****
   7.mo:Expected error in mat bytes-allocated: "bytes-allocated: invalid space gnu".
   7.mo:Expected error in mat error: "a: hit me!".
   7.mo:Expected error in mat error: "f: n is 0".
@@ -214,7 +214,7 @@
   record.mo:Expected error in mat record2: "invalid value 3 for foreign type double-float".
   record.mo:Expected error in mat record2: "3 is not of type #<record type fudge>".
   record.mo:Expected error in mat record2: "make-record-type: invalid field list ((immutable double-float a) . b)".
---- 7050,7057 ----
+--- 7095,7102 ----
   7.mo:Expected error in mat bytes-allocated: "bytes-allocated: invalid space gnu".
   7.mo:Expected error in mat error: "a: hit me!".
   7.mo:Expected error in mat error: "f: n is 0".
@@ -224,7 +224,7 @@
   record.mo:Expected error in mat record2: "3 is not of type #<record type fudge>".
   record.mo:Expected error in mat record2: "make-record-type: invalid field list ((immutable double-float a) . b)".
 ***************
-*** 7059,7073 ****
+*** 7104,7118 ****
   record.mo:Expected error in mat type-descriptor: "invalid syntax (type-descriptor 3)".
   record.mo:Expected error in mat type-descriptor: "type-descriptor: unrecognized record car".
   record.mo:Expected error in mat record3: "variable set-fudge-a! is not bound".
@@ -240,7 +240,7 @@
   record.mo:Expected error in mat record9: "record-reader: invalid input #f".
   record.mo:Expected error in mat record9: "record-reader: invalid second argument fudge".
   record.mo:Expected error in mat record9: "record-reader: invalid second argument fudge".
---- 7059,7073 ----
+--- 7104,7118 ----
   record.mo:Expected error in mat type-descriptor: "invalid syntax (type-descriptor 3)".
   record.mo:Expected error in mat type-descriptor: "type-descriptor: unrecognized record car".
   record.mo:Expected error in mat record3: "variable set-fudge-a! is not bound".
@@ -257,7 +257,7 @@
   record.mo:Expected error in mat record9: "record-reader: invalid second argument fudge".
   record.mo:Expected error in mat record9: "record-reader: invalid second argument fudge".
 ***************
-*** 7080,7105 ****
+*** 7125,7150 ****
   record.mo:Expected error in mat record10: "read: unresolvable cycle constructing record of type #<record type bar> at char 3 of #<input port string>".
   record.mo:Expected error in mat record16: "read: unresolvable cycle constructing record of type #<record type bazar> at char 3 of #<input port string>".
   record.mo:Expected error in mat record16: "read: unresolvable cycle constructing record of type #<record type bazar> at char 3 of #<input port string>".
@@ -284,7 +284,7 @@
   record.mo:Expected error in mat foreign-data: "foreign-alloc: 0 is not a positive fixnum".
   record.mo:Expected error in mat foreign-data: "foreign-alloc: <int> is not a positive fixnum".
   record.mo:Expected error in mat foreign-data: "foreign-alloc: -5 is not a positive fixnum".
---- 7080,7105 ----
+--- 7125,7150 ----
   record.mo:Expected error in mat record10: "read: unresolvable cycle constructing record of type #<record type bar> at char 3 of #<input port string>".
   record.mo:Expected error in mat record16: "read: unresolvable cycle constructing record of type #<record type bazar> at char 3 of #<input port string>".
   record.mo:Expected error in mat record16: "read: unresolvable cycle constructing record of type #<record type bazar> at char 3 of #<input port string>".
@@ -312,7 +312,7 @@
   record.mo:Expected error in mat foreign-data: "foreign-alloc: <int> is not a positive fixnum".
   record.mo:Expected error in mat foreign-data: "foreign-alloc: -5 is not a positive fixnum".
 ***************
-*** 7221,7259 ****
+*** 7266,7304 ****
   record.mo:Expected error in mat record22: "invalid field specifier (immutable creepy q)".
   record.mo:Expected error in mat record22: "invalid field specifier (immutable creepy q)".
   record.mo:Expected error in mat record23: "make-record-type: cannot extend sealed record type #<record type foo>".
@@ -352,7 +352,7 @@
   record.mo:Expected error in mat record?: "record?: 4 is not a record type descriptor".
   record.mo:Expected error in mat record?: "record?: a is not a record type descriptor".
   record.mo:Expected error in mat record?: "record?: #(1) is not a record type descriptor".
---- 7221,7259 ----
+--- 7266,7304 ----
   record.mo:Expected error in mat record22: "invalid field specifier (immutable creepy q)".
   record.mo:Expected error in mat record22: "invalid field specifier (immutable creepy q)".
   record.mo:Expected error in mat record23: "make-record-type: cannot extend sealed record type #<record type foo>".
@@ -393,7 +393,7 @@
   record.mo:Expected error in mat record?: "record?: a is not a record type descriptor".
   record.mo:Expected error in mat record?: "record?: #(1) is not a record type descriptor".
 ***************
-*** 7268,7324 ****
+*** 7313,7369 ****
   record.mo:Expected error in mat r6rs-records-procedural: "make-record-constructor-descriptor: invalid protocol flimflam".
   record.mo:Expected error in mat r6rs-records-procedural: "attempt to apply non-procedure not-a-procedure".
   record.mo:Expected error in mat r6rs-records-procedural: "attempt to apply non-procedure spam".
@@ -451,7 +451,7 @@
   record.mo:Expected error in mat r6rs-records-syntactic: "define-record-type: incompatible record type cpoint - different parent".
   record.mo:Expected error in mat r6rs-records-syntactic: "define-record-type: incompatible record type cpoint - different parent".
   record.mo:Expected error in mat r6rs-records-syntactic: "cannot extend define-record-type parent fratrat".
---- 7268,7324 ----
+--- 7313,7369 ----
   record.mo:Expected error in mat r6rs-records-procedural: "make-record-constructor-descriptor: invalid protocol flimflam".
   record.mo:Expected error in mat r6rs-records-procedural: "attempt to apply non-procedure not-a-procedure".
   record.mo:Expected error in mat r6rs-records-procedural: "attempt to apply non-procedure spam".
@@ -510,7 +510,7 @@
   record.mo:Expected error in mat r6rs-records-syntactic: "define-record-type: incompatible record type cpoint - different parent".
   record.mo:Expected error in mat r6rs-records-syntactic: "cannot extend define-record-type parent fratrat".
 ***************
-*** 8406,8418 ****
+*** 8451,8463 ****
   fx.mo:Expected error in mat r6rs:fx-: "fx-: #f is not a fixnum".
   fx.mo:Expected error in mat r6rs:fx-: "fx-: #f is not a fixnum".
   fx.mo:Expected error in mat fx*: "fx*: (a . b) is not a fixnum".
@@ -524,7 +524,7 @@
   fx.mo:Expected error in mat r6rs:fx*: "fx*: <int> is not a fixnum".
   fx.mo:Expected error in mat r6rs:fx*: "fx*: <-int> is not a fixnum".
   fx.mo:Expected error in mat r6rs:fx*: "fx*: #f is not a fixnum".
---- 8406,8418 ----
+--- 8451,8463 ----
   fx.mo:Expected error in mat r6rs:fx-: "fx-: #f is not a fixnum".
   fx.mo:Expected error in mat r6rs:fx-: "fx-: #f is not a fixnum".
   fx.mo:Expected error in mat fx*: "fx*: (a . b) is not a fixnum".
@@ -539,7 +539,7 @@
   fx.mo:Expected error in mat r6rs:fx*: "fx*: <-int> is not a fixnum".
   fx.mo:Expected error in mat r6rs:fx*: "fx*: #f is not a fixnum".
 ***************
-*** 9876,9885 ****
+*** 9921,9930 ****
   exceptions.mo:Expected error in mat assert: "failed assertion (memq (quote b) (quote (1 2 a 3 4)))".
   exceptions.mo:Expected error in mat assert: "failed assertion (q ...)".
   exceptions.mo:Expected error in mat assert: "failed assertion (andmap symbol? (syntax (x ...)))".
@@ -550,7 +550,7 @@
   oop.mo:Expected error in mat oop: "m1: not applicable to 17".
   oop.mo:Expected error in mat oop: "variable <a>-x1 is not bound".
   oop.mo:Expected error in mat oop: "variable <a>-x1-set! is not bound".
---- 9876,9885 ----
+--- 9921,9930 ----
   exceptions.mo:Expected error in mat assert: "failed assertion (memq (quote b) (quote (1 2 a 3 4)))".
   exceptions.mo:Expected error in mat assert: "failed assertion (q ...)".
   exceptions.mo:Expected error in mat assert: "failed assertion (andmap symbol? (syntax (x ...)))".
diff --git a/mats/patch-interpret-3-f-f-f b/mats/patch-interpret-3-f-f-f
index 4b35daeb48..1257f33134 100644
--- a/mats/patch-interpret-3-f-f-f
+++ b/mats/patch-interpret-3-f-f-f
@@ -1,5 +1,5 @@
-*** errors-compile-3-f-f-f	2016-05-01 13:15:04.367323263 -0400
---- errors-interpret-3-f-f-f	2016-05-01 13:42:18.210493401 -0400
+*** errors-compile-3-f-f-f	2017-03-14 23:50:07.000000000 -0400
+--- errors-interpret-3-f-f-f	2017-03-15 00:26:52.000000000 -0400
 ***************
 *** 1,3 ****
 --- 1,9 ----
diff --git a/mats/patch-interpret-3-f-t-f b/mats/patch-interpret-3-f-t-f
index 1b69b44f3c..080fd2cbe3 100644
--- a/mats/patch-interpret-3-f-t-f
+++ b/mats/patch-interpret-3-f-t-f
@@ -1,5 +1,5 @@
-*** errors-compile-3-f-t-f	2016-05-01 13:19:46.141964962 -0400
---- errors-interpret-3-f-t-f	2016-05-01 13:34:49.880630639 -0400
+*** errors-compile-3-f-t-f	2017-03-14 23:56:31.000000000 -0400
+--- errors-interpret-3-f-t-f	2017-03-15 00:17:15.000000000 -0400
 ***************
 *** 1,3 ****
 --- 1,9 ----
diff --git a/mats/root-experr-compile-0-f-f-f b/mats/root-experr-compile-0-f-f-f
index 3a6075d336..456c44da9a 100644
--- a/mats/root-experr-compile-0-f-f-f
+++ b/mats/root-experr-compile-0-f-f-f
@@ -1968,7 +1968,7 @@ primvars.mo:Expected error in mat trace-output-port: "trace-output-port: #<input
 5_5.mo:Expected error in mat make-string: "incorrect argument count in call (make-string)".
 5_5.mo:Expected error in mat make-string: "incorrect argument count in call (make-string 2 #\a #\b)".
 5_5.mo:Expected error in mat make-string: "make-string: a is not a character".
-5_5.mo:Expected error in mat make-string: "make-string: a is not a nonnegative fixnum".
+5_5.mo:Expected error in mat make-string: "make-string: a is not a valid string length".
 5_5.mo:Expected error in mat string-length: "incorrect argument count in call (string-length)".
 5_5.mo:Expected error in mat string-length: "incorrect argument count in call (string-length "hi" "there")".
 5_5.mo:Expected error in mat string-length: "string-length: a is not a string".
@@ -1983,7 +1983,7 @@ primvars.mo:Expected error in mat trace-output-port: "trace-output-port: #<input
 5_5.mo:Expected error in mat string-set!: "incorrect argument count in call (string-set! "hi")".
 5_5.mo:Expected error in mat string-set!: "incorrect argument count in call (string-set! "hi" 1)".
 5_5.mo:Expected error in mat string-set!: "incorrect argument count in call (string-set! "hi" 3 #\a #\b)".
-5_5.mo:Expected error in mat string-set!: "string-set!: a is not a string".
+5_5.mo:Expected error in mat string-set!: "string-set!: a is not a mutable string".
 5_5.mo:Expected error in mat string-set!: "string-set!: a is not a valid index for "hi"".
 5_5.mo:Expected error in mat string-set!: "string-set!: 3 is not a valid index for "hi"".
 5_5.mo:Expected error in mat string-set!: "string-set!: -1 is not a valid index for "hi"".
@@ -1999,7 +1999,7 @@ primvars.mo:Expected error in mat trace-output-port: "trace-output-port: #<input
 5_5.mo:Expected error in mat string-copy!: "incorrect argument count in call (string-copy! $s2 3 $s1 1)".
 5_5.mo:Expected error in mat string-copy!: "incorrect argument count in call (string-copy! $s2 3 $s1 1 2 ...)".
 5_5.mo:Expected error in mat string-copy!: "string-copy!: 0 is not a string".
-5_5.mo:Expected error in mat string-copy!: "string-copy!: #vu8(1 2 3) is not a string".
+5_5.mo:Expected error in mat string-copy!: "string-copy!: #vu8(1 2 3) is not a mutable string".
 5_5.mo:Expected error in mat string-copy!: "string-copy!: invalid start value -1".
 5_5.mo:Expected error in mat string-copy!: "string-copy!: invalid start value -1".
 5_5.mo:Expected error in mat string-copy!: "string-copy!: invalid start value a".
@@ -2024,8 +2024,8 @@ primvars.mo:Expected error in mat trace-output-port: "trace-output-port: #<input
 5_5.mo:Expected error in mat string-truncate!: "incorrect argument count in call (string-truncate!)".
 5_5.mo:Expected error in mat string-truncate!: "incorrect argument count in call (string-truncate! $s)".
 5_5.mo:Expected error in mat string-truncate!: "incorrect argument count in call (string-truncate! $s 3 15)".
-5_5.mo:Expected error in mat string-truncate!: "string-truncate!: 0 is not a string".
-5_5.mo:Expected error in mat string-truncate!: "string-truncate!: #vu8(1 2 3) is not a string".
+5_5.mo:Expected error in mat string-truncate!: "string-truncate!: 0 is not a mutable string".
+5_5.mo:Expected error in mat string-truncate!: "string-truncate!: #vu8(1 2 3) is not a mutable string".
 5_5.mo:Expected error in mat string-truncate!: "string-truncate!: invalid new length -1 for "abcdefghi"".
 5_5.mo:Expected error in mat string-truncate!: "string-truncate!: invalid new length 10 for "abcdefghi"".
 5_5.mo:Expected error in mat string-truncate!: "string-truncate!: invalid new length 1000 for "abcdefghi"".
@@ -2049,14 +2049,14 @@ primvars.mo:Expected error in mat trace-output-port: "trace-output-port: #<input
 5_5.mo:Expected error in mat string-fill!: "incorrect argument count in call (string-fill! "hi")".
 5_5.mo:Expected error in mat string-fill!: "incorrect argument count in call (string-fill! "hi" #\a #\b)".
 5_5.mo:Expected error in mat string-fill!: "string-fill!: a is not a character".
-5_5.mo:Expected error in mat string-fill!: "string-fill!: a is not a string".
+5_5.mo:Expected error in mat string-fill!: "string-fill!: a is not a mutable string".
 5_5.mo:Expected error in mat substring-fill!: "incorrect argument count in call (substring-fill!)".
 5_5.mo:Expected error in mat substring-fill!: "incorrect argument count in call (substring-fill! "hi")".
 5_5.mo:Expected error in mat substring-fill!: "incorrect argument count in call (substring-fill! "hi" 0)".
 5_5.mo:Expected error in mat substring-fill!: "incorrect argument count in call (substring-fill! "hi" 0 2)".
 5_5.mo:Expected error in mat substring-fill!: "substring-fill!: 0 and 3 are not valid start/end indices for "hi"".
 5_5.mo:Expected error in mat substring-fill!: "substring-fill!: -1 and 3 are not valid start/end indices for "hi"".
-5_5.mo:Expected error in mat substring-fill!: "substring-fill!: a is not a string".
+5_5.mo:Expected error in mat substring-fill!: "substring-fill!: a is not a mutable string".
 5_5.mo:Expected error in mat substring-fill!: "substring-fill!: 0 and a are not valid start/end indices for "hi"".
 5_5.mo:Expected error in mat substring-fill!: "substring-fill!: 1 and 0 are not valid start/end indices for "hi"".
 5_5.mo:Expected error in mat list->string: "incorrect argument count in call (list->string)".
@@ -2068,6 +2068,11 @@ primvars.mo:Expected error in mat trace-output-port: "trace-output-port: #<input
 5_5.mo:Expected error in mat string->list: "incorrect argument count in call (string->list)".
 5_5.mo:Expected error in mat string->list: "incorrect argument count in call (string->list "ab" "cd")".
 5_5.mo:Expected error in mat string->list: "string->list: a is not a string".
+5_5.mo:Expected error in mat string->immutable-string: "string-set!: "abc" is not a mutable string".
+5_5.mo:Expected error in mat string->immutable-string: "string-fill!: "abc" is not a mutable string".
+5_5.mo:Expected error in mat string->immutable-string: "substring-fill!: "abc" is not a mutable string".
+5_5.mo:Expected error in mat string->immutable-string: "string-copy!: "abc" is not a mutable string".
+5_5.mo:Expected error in mat string->immutable-string: "string-truncate!: "abc" is not a mutable string".
 bytevector.mo:Expected error in mat native-endianness: "incorrect argument count in call (native-endianness (quote big))".
 bytevector.mo:Expected error in mat endianness: "invalid endianness spam".
 bytevector.mo:Expected error in mat endianness: "invalid endianness (quote big)".
@@ -2077,11 +2082,11 @@ bytevector.mo:Expected error in mat endianness: "invalid syntax (endianness . bi
 bytevector.mo:Expected error in mat endianness: "invalid syntax (endianness big little)".
 bytevector.mo:Expected error in mat make-bytevector: "incorrect argument count in call (make-bytevector)".
 bytevector.mo:Expected error in mat make-bytevector: "incorrect argument count in call (make-bytevector 0 0 0)".
-bytevector.mo:Expected error in mat make-bytevector: "make-bytevector: -1 is not a nonnegative fixnum".
-bytevector.mo:Expected error in mat make-bytevector: "make-bytevector: -1 is not a nonnegative fixnum".
-bytevector.mo:Expected error in mat make-bytevector: "make-bytevector: <int> is not a nonnegative fixnum".
-bytevector.mo:Expected error in mat make-bytevector: "make-bytevector: <int> is not a nonnegative fixnum".
-bytevector.mo:Expected error in mat make-bytevector: "make-bytevector: a is not a nonnegative fixnum".
+bytevector.mo:Expected error in mat make-bytevector: "make-bytevector: -1 is not a valid bytevector length".
+bytevector.mo:Expected error in mat make-bytevector: "make-bytevector: -1 is not a valid bytevector length".
+bytevector.mo:Expected error in mat make-bytevector: "make-bytevector: <int> is not a valid bytevector length".
+bytevector.mo:Expected error in mat make-bytevector: "make-bytevector: <int> is not a valid bytevector length".
+bytevector.mo:Expected error in mat make-bytevector: "make-bytevector: a is not a valid bytevector length".
 bytevector.mo:Expected error in mat make-bytevector: "make-bytevector: a is not a valid fill value".
 bytevector.mo:Expected error in mat make-bytevector: "make-bytevector: 256 is not a valid fill value".
 bytevector.mo:Expected error in mat make-bytevector: "make-bytevector: -129 is not a valid fill value".
@@ -2117,8 +2122,8 @@ bytevector.mo:Expected error in mat bytevector-s8-set!: "incorrect argument coun
 bytevector.mo:Expected error in mat bytevector-s8-set!: "incorrect argument count in call (bytevector-s8-set! $v1)".
 bytevector.mo:Expected error in mat bytevector-s8-set!: "incorrect argument count in call (bytevector-s8-set! $v1 2)".
 bytevector.mo:Expected error in mat bytevector-s8-set!: "incorrect argument count in call (bytevector-s8-set! $v1 2 3 4)".
-bytevector.mo:Expected error in mat bytevector-s8-set!: "bytevector-s8-set!: (3 4 5) is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-s8-set!: "bytevector-s8-set!: (3 4 5) is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-s8-set!: "bytevector-s8-set!: (3 4 5) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector-s8-set!: "bytevector-s8-set!: (3 4 5) is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-s8-set!: "bytevector-s8-set!: 3 is not a valid index for #vu8(3 4 5)".
 bytevector.mo:Expected error in mat bytevector-s8-set!: "bytevector-s8-set!: -1 is not a valid index for #vu8(3 4 5)".
 bytevector.mo:Expected error in mat bytevector-s8-set!: "bytevector-s8-set!: a is not a valid index for #vu8(3 4 5)".
@@ -2129,8 +2134,8 @@ bytevector.mo:Expected error in mat bytevector-u8-set!: "incorrect argument coun
 bytevector.mo:Expected error in mat bytevector-u8-set!: "incorrect argument count in call (bytevector-u8-set! $v1)".
 bytevector.mo:Expected error in mat bytevector-u8-set!: "incorrect argument count in call (bytevector-u8-set! $v1 2)".
 bytevector.mo:Expected error in mat bytevector-u8-set!: "incorrect argument count in call (bytevector-u8-set! $v1 2 3 4)".
-bytevector.mo:Expected error in mat bytevector-u8-set!: "bytevector-u8-set!: (3 4 5) is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-u8-set!: "bytevector-u8-set!: (3 4 5) is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-u8-set!: "bytevector-u8-set!: (3 4 5) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector-u8-set!: "bytevector-u8-set!: (3 4 5) is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-u8-set!: "bytevector-u8-set!: 3 is not a valid index for #vu8(3 4 5)".
 bytevector.mo:Expected error in mat bytevector-u8-set!: "bytevector-u8-set!: -1 is not a valid index for #vu8(3 4 5)".
 bytevector.mo:Expected error in mat bytevector-u8-set!: "bytevector-u8-set!: a is not a valid index for #vu8(3 4 5)".
@@ -2161,8 +2166,8 @@ bytevector.mo:Expected error in mat bytevector-s16-native-set!: "incorrect argum
 bytevector.mo:Expected error in mat bytevector-s16-native-set!: "incorrect argument count in call (bytevector-s16-native-set! $v1)".
 bytevector.mo:Expected error in mat bytevector-s16-native-set!: "incorrect argument count in call (bytevector-s16-native-set! $v1 0)".
 bytevector.mo:Expected error in mat bytevector-s16-native-set!: "incorrect argument count in call (bytevector-s16-native-set! $v1 0 0 15)".
-bytevector.mo:Expected error in mat bytevector-s16-native-set!: "bytevector-s16-native-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-s16-native-set!: "bytevector-s16-native-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-s16-native-set!: "bytevector-s16-native-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector-s16-native-set!: "bytevector-s16-native-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-s16-native-set!: "bytevector-s16-native-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-s16-native-set!: "bytevector-s16-native-set!: invalid index 1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-s16-native-set!: "bytevector-s16-native-set!: invalid index 3 for bytevector #vu8(173 173 173 173 173 173 ...)".
@@ -2178,8 +2183,8 @@ bytevector.mo:Expected error in mat bytevector-u16-native-set!: "incorrect argum
 bytevector.mo:Expected error in mat bytevector-u16-native-set!: "incorrect argument count in call (bytevector-u16-native-set! $v1)".
 bytevector.mo:Expected error in mat bytevector-u16-native-set!: "incorrect argument count in call (bytevector-u16-native-set! $v1 0)".
 bytevector.mo:Expected error in mat bytevector-u16-native-set!: "incorrect argument count in call (bytevector-u16-native-set! $v1 0 0 15)".
-bytevector.mo:Expected error in mat bytevector-u16-native-set!: "bytevector-u16-native-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-u16-native-set!: "bytevector-u16-native-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-u16-native-set!: "bytevector-u16-native-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector-u16-native-set!: "bytevector-u16-native-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-u16-native-set!: "bytevector-u16-native-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-u16-native-set!: "bytevector-u16-native-set!: invalid index 1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-u16-native-set!: "bytevector-u16-native-set!: invalid index 3 for bytevector #vu8(173 173 173 173 173 173 ...)".
@@ -2219,8 +2224,8 @@ bytevector.mo:Expected error in mat bytevector-s16-set!: "incorrect argument cou
 bytevector.mo:Expected error in mat bytevector-s16-set!: "incorrect argument count in call (bytevector-s16-set! $v1)".
 bytevector.mo:Expected error in mat bytevector-s16-set!: "incorrect argument count in call (bytevector-s16-set! $v1 0 0)".
 bytevector.mo:Expected error in mat bytevector-s16-set!: "incorrect argument count in call (bytevector-s16-set! $v1 0 0 0 (native-endianness))".
-bytevector.mo:Expected error in mat bytevector-s16-set!: "bytevector-s16-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-s16-set!: "bytevector-s16-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-s16-set!: "bytevector-s16-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector-s16-set!: "bytevector-s16-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-s16-set!: "bytevector-s16-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-s16-set!: "bytevector-s16-set!: invalid index 10 for 2-byte field of bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-s16-set!: "bytevector-s16-set!: invalid index 11 for bytevector #vu8(173 173 173 173 173 173 ...)".
@@ -2238,8 +2243,8 @@ bytevector.mo:Expected error in mat bytevector-u16-set!: "incorrect argument cou
 bytevector.mo:Expected error in mat bytevector-u16-set!: "incorrect argument count in call (bytevector-u16-set! $v1)".
 bytevector.mo:Expected error in mat bytevector-u16-set!: "incorrect argument count in call (bytevector-u16-set! $v1 0 0)".
 bytevector.mo:Expected error in mat bytevector-u16-set!: "incorrect argument count in call (bytevector-u16-set! $v1 0 0 0 (native-endianness))".
-bytevector.mo:Expected error in mat bytevector-u16-set!: "bytevector-u16-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-u16-set!: "bytevector-u16-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-u16-set!: "bytevector-u16-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector-u16-set!: "bytevector-u16-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-u16-set!: "bytevector-u16-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-u16-set!: "bytevector-u16-set!: invalid index 10 for 2-byte field of bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-u16-set!: "bytevector-u16-set!: invalid index 11 for bytevector #vu8(173 173 173 173 173 173 ...)".
@@ -2284,8 +2289,8 @@ bytevector.mo:Expected error in mat bytevector-s24-set!: "incorrect argument cou
 bytevector.mo:Expected error in mat bytevector-s24-set!: "incorrect argument count in call (bytevector-s24-set! $v1 0)".
 bytevector.mo:Expected error in mat bytevector-s24-set!: "incorrect argument count in call (bytevector-s24-set! $v1 0 0)".
 bytevector.mo:Expected error in mat bytevector-s24-set!: "incorrect argument count in call (bytevector-s24-set! $v1 0 0 (quote big) 0)".
-bytevector.mo:Expected error in mat bytevector-s24-set!: "bytevector-s24-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-s24-set!: "bytevector-s24-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-s24-set!: "bytevector-s24-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector-s24-set!: "bytevector-s24-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-s24-set!: "bytevector-s24-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-s24-set!: "bytevector-s24-set!: invalid index 21 for 3-byte field of bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-s24-set!: "bytevector-s24-set!: invalid index 22 for 3-byte field of bytevector #vu8(173 173 173 173 173 173 ...)".
@@ -2302,8 +2307,8 @@ bytevector.mo:Expected error in mat bytevector-u24-set!: "incorrect argument cou
 bytevector.mo:Expected error in mat bytevector-u24-set!: "incorrect argument count in call (bytevector-u24-set! $v1 0)".
 bytevector.mo:Expected error in mat bytevector-u24-set!: "incorrect argument count in call (bytevector-u24-set! $v1 0 0)".
 bytevector.mo:Expected error in mat bytevector-u24-set!: "incorrect argument count in call (bytevector-u24-set! $v1 0 0 (quote big) 0)".
-bytevector.mo:Expected error in mat bytevector-u24-set!: "bytevector-u24-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-u24-set!: "bytevector-u24-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-u24-set!: "bytevector-u24-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector-u24-set!: "bytevector-u24-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-u24-set!: "bytevector-u24-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-u24-set!: "bytevector-u24-set!: invalid index 21 for 3-byte field of bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-u24-set!: "bytevector-u24-set!: invalid index 22 for 3-byte field of bytevector #vu8(173 173 173 173 173 173 ...)".
@@ -2347,8 +2352,8 @@ bytevector.mo:Expected error in mat bytevector-s32-native-set!: "incorrect argum
 bytevector.mo:Expected error in mat bytevector-s32-native-set!: "incorrect argument count in call (bytevector-s32-native-set! $v1)".
 bytevector.mo:Expected error in mat bytevector-s32-native-set!: "incorrect argument count in call (bytevector-s32-native-set! $v1 0)".
 bytevector.mo:Expected error in mat bytevector-s32-native-set!: "incorrect argument count in call (bytevector-s32-native-set! $v1 0 0 15)".
-bytevector.mo:Expected error in mat bytevector-s32-native-set!: "bytevector-s32-native-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-s32-native-set!: "bytevector-s32-native-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-s32-native-set!: "bytevector-s32-native-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector-s32-native-set!: "bytevector-s32-native-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-s32-native-set!: "bytevector-s32-native-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-s32-native-set!: "bytevector-s32-native-set!: invalid index 1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-s32-native-set!: "bytevector-s32-native-set!: invalid index 2 for bytevector #vu8(173 173 173 173 173 173 ...)".
@@ -2377,8 +2382,8 @@ bytevector.mo:Expected error in mat bytevector-u32-native-set!: "incorrect argum
 bytevector.mo:Expected error in mat bytevector-u32-native-set!: "incorrect argument count in call (bytevector-u32-native-set! $v1)".
 bytevector.mo:Expected error in mat bytevector-u32-native-set!: "incorrect argument count in call (bytevector-u32-native-set! $v1 0)".
 bytevector.mo:Expected error in mat bytevector-u32-native-set!: "incorrect argument count in call (bytevector-u32-native-set! $v1 0 0 15)".
-bytevector.mo:Expected error in mat bytevector-u32-native-set!: "bytevector-u32-native-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-u32-native-set!: "bytevector-u32-native-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-u32-native-set!: "bytevector-u32-native-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector-u32-native-set!: "bytevector-u32-native-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-u32-native-set!: "bytevector-u32-native-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-u32-native-set!: "bytevector-u32-native-set!: invalid index 1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-u32-native-set!: "bytevector-u32-native-set!: invalid index 2 for bytevector #vu8(173 173 173 173 173 173 ...)".
@@ -2434,8 +2439,8 @@ bytevector.mo:Expected error in mat bytevector-s32-set!: "incorrect argument cou
 bytevector.mo:Expected error in mat bytevector-s32-set!: "incorrect argument count in call (bytevector-s32-set! $v1 0)".
 bytevector.mo:Expected error in mat bytevector-s32-set!: "incorrect argument count in call (bytevector-s32-set! $v1 0 0)".
 bytevector.mo:Expected error in mat bytevector-s32-set!: "incorrect argument count in call (bytevector-s32-set! $v1 0 0 (quote big) 0)".
-bytevector.mo:Expected error in mat bytevector-s32-set!: "bytevector-s32-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-s32-set!: "bytevector-s32-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-s32-set!: "bytevector-s32-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector-s32-set!: "bytevector-s32-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-s32-set!: "bytevector-s32-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-s32-set!: "bytevector-s32-set!: invalid index 20 for 4-byte field of bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-s32-set!: "bytevector-s32-set!: invalid index 21 for 4-byte field of bytevector #vu8(173 173 173 173 173 173 ...)".
@@ -2453,8 +2458,8 @@ bytevector.mo:Expected error in mat bytevector-u32-set!: "incorrect argument cou
 bytevector.mo:Expected error in mat bytevector-u32-set!: "incorrect argument count in call (bytevector-u32-set! $v1 0)".
 bytevector.mo:Expected error in mat bytevector-u32-set!: "incorrect argument count in call (bytevector-u32-set! $v1 0 0)".
 bytevector.mo:Expected error in mat bytevector-u32-set!: "incorrect argument count in call (bytevector-u32-set! $v1 0 0 (quote big) 0)".
-bytevector.mo:Expected error in mat bytevector-u32-set!: "bytevector-u32-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-u32-set!: "bytevector-u32-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-u32-set!: "bytevector-u32-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector-u32-set!: "bytevector-u32-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-u32-set!: "bytevector-u32-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-u32-set!: "bytevector-u32-set!: invalid index 20 for 4-byte field of bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-u32-set!: "bytevector-u32-set!: invalid index 21 for 4-byte field of bytevector #vu8(173 173 173 173 173 173 ...)".
@@ -2498,8 +2503,8 @@ bytevector.mo:Expected error in mat bytevector-s40-set!: "incorrect argument cou
 bytevector.mo:Expected error in mat bytevector-s40-set!: "incorrect argument count in call (bytevector-s40-set! $v1 0)".
 bytevector.mo:Expected error in mat bytevector-s40-set!: "incorrect argument count in call (bytevector-s40-set! $v1 0 0)".
 bytevector.mo:Expected error in mat bytevector-s40-set!: "incorrect argument count in call (bytevector-s40-set! $v1 0 0 (quote big) 0)".
-bytevector.mo:Expected error in mat bytevector-s40-set!: "bytevector-s40-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-s40-set!: "bytevector-s40-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-s40-set!: "bytevector-s40-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector-s40-set!: "bytevector-s40-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-s40-set!: "bytevector-s40-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-s40-set!: "bytevector-s40-set!: invalid index 19 for 5-byte field of bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-s40-set!: "bytevector-s40-set!: invalid index 22 for 5-byte field of bytevector #vu8(173 173 173 173 173 173 ...)".
@@ -2516,8 +2521,8 @@ bytevector.mo:Expected error in mat bytevector-u40-set!: "incorrect argument cou
 bytevector.mo:Expected error in mat bytevector-u40-set!: "incorrect argument count in call (bytevector-u40-set! $v1 0)".
 bytevector.mo:Expected error in mat bytevector-u40-set!: "incorrect argument count in call (bytevector-u40-set! $v1 0 0)".
 bytevector.mo:Expected error in mat bytevector-u40-set!: "incorrect argument count in call (bytevector-u40-set! $v1 0 0 (quote big) 0)".
-bytevector.mo:Expected error in mat bytevector-u40-set!: "bytevector-u40-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-u40-set!: "bytevector-u40-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-u40-set!: "bytevector-u40-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector-u40-set!: "bytevector-u40-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-u40-set!: "bytevector-u40-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-u40-set!: "bytevector-u40-set!: invalid index 19 for 5-byte field of bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-u40-set!: "bytevector-u40-set!: invalid index 22 for 5-byte field of bytevector #vu8(173 173 173 173 173 173 ...)".
@@ -2560,8 +2565,8 @@ bytevector.mo:Expected error in mat bytevector-s48-set!: "incorrect argument cou
 bytevector.mo:Expected error in mat bytevector-s48-set!: "incorrect argument count in call (bytevector-s48-set! $v1 0)".
 bytevector.mo:Expected error in mat bytevector-s48-set!: "incorrect argument count in call (bytevector-s48-set! $v1 0 0)".
 bytevector.mo:Expected error in mat bytevector-s48-set!: "incorrect argument count in call (bytevector-s48-set! $v1 0 0 (quote big) 0)".
-bytevector.mo:Expected error in mat bytevector-s48-set!: "bytevector-s48-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-s48-set!: "bytevector-s48-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-s48-set!: "bytevector-s48-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector-s48-set!: "bytevector-s48-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-s48-set!: "bytevector-s48-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-s48-set!: "bytevector-s48-set!: invalid index 18 for 6-byte field of bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-s48-set!: "bytevector-s48-set!: invalid index 22 for 6-byte field of bytevector #vu8(173 173 173 173 173 173 ...)".
@@ -2578,8 +2583,8 @@ bytevector.mo:Expected error in mat bytevector-u48-set!: "incorrect argument cou
 bytevector.mo:Expected error in mat bytevector-u48-set!: "incorrect argument count in call (bytevector-u48-set! $v1 0)".
 bytevector.mo:Expected error in mat bytevector-u48-set!: "incorrect argument count in call (bytevector-u48-set! $v1 0 0)".
 bytevector.mo:Expected error in mat bytevector-u48-set!: "incorrect argument count in call (bytevector-u48-set! $v1 0 0 (quote big) 0)".
-bytevector.mo:Expected error in mat bytevector-u48-set!: "bytevector-u48-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-u48-set!: "bytevector-u48-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-u48-set!: "bytevector-u48-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector-u48-set!: "bytevector-u48-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-u48-set!: "bytevector-u48-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-u48-set!: "bytevector-u48-set!: invalid index 18 for 6-byte field of bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-u48-set!: "bytevector-u48-set!: invalid index 22 for 6-byte field of bytevector #vu8(173 173 173 173 173 173 ...)".
@@ -2622,8 +2627,8 @@ bytevector.mo:Expected error in mat bytevector-s56-set!: "incorrect argument cou
 bytevector.mo:Expected error in mat bytevector-s56-set!: "incorrect argument count in call (bytevector-s56-set! $v1 0)".
 bytevector.mo:Expected error in mat bytevector-s56-set!: "incorrect argument count in call (bytevector-s56-set! $v1 0 0)".
 bytevector.mo:Expected error in mat bytevector-s56-set!: "incorrect argument count in call (bytevector-s56-set! $v1 0 0 (quote big) 0)".
-bytevector.mo:Expected error in mat bytevector-s56-set!: "bytevector-s56-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-s56-set!: "bytevector-s56-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-s56-set!: "bytevector-s56-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector-s56-set!: "bytevector-s56-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-s56-set!: "bytevector-s56-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-s56-set!: "bytevector-s56-set!: invalid index 17 for 7-byte field of bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-s56-set!: "bytevector-s56-set!: invalid index 22 for 7-byte field of bytevector #vu8(173 173 173 173 173 173 ...)".
@@ -2640,8 +2645,8 @@ bytevector.mo:Expected error in mat bytevector-u56-set!: "incorrect argument cou
 bytevector.mo:Expected error in mat bytevector-u56-set!: "incorrect argument count in call (bytevector-u56-set! $v1 0)".
 bytevector.mo:Expected error in mat bytevector-u56-set!: "incorrect argument count in call (bytevector-u56-set! $v1 0 0)".
 bytevector.mo:Expected error in mat bytevector-u56-set!: "incorrect argument count in call (bytevector-u56-set! $v1 0 0 (quote big) 0)".
-bytevector.mo:Expected error in mat bytevector-u56-set!: "bytevector-u56-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-u56-set!: "bytevector-u56-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-u56-set!: "bytevector-u56-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector-u56-set!: "bytevector-u56-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-u56-set!: "bytevector-u56-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-u56-set!: "bytevector-u56-set!: invalid index 17 for 7-byte field of bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-u56-set!: "bytevector-u56-set!: invalid index 22 for 7-byte field of bytevector #vu8(173 173 173 173 173 173 ...)".
@@ -2721,8 +2726,8 @@ bytevector.mo:Expected error in mat bytevector-s64-native-set!: "incorrect argum
 bytevector.mo:Expected error in mat bytevector-s64-native-set!: "incorrect argument count in call (bytevector-s64-native-set! $v1)".
 bytevector.mo:Expected error in mat bytevector-s64-native-set!: "incorrect argument count in call (bytevector-s64-native-set! $v1 0)".
 bytevector.mo:Expected error in mat bytevector-s64-native-set!: "incorrect argument count in call (bytevector-s64-native-set! $v1 0 0 15)".
-bytevector.mo:Expected error in mat bytevector-s64-native-set!: "bytevector-s64-native-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-s64-native-set!: "bytevector-s64-native-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-s64-native-set!: "bytevector-s64-native-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector-s64-native-set!: "bytevector-s64-native-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-s64-native-set!: "bytevector-s64-native-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-s64-native-set!: "bytevector-s64-native-set!: invalid index 1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-s64-native-set!: "bytevector-s64-native-set!: invalid index 2 for bytevector #vu8(173 173 173 173 173 173 ...)".
@@ -2758,8 +2763,8 @@ bytevector.mo:Expected error in mat bytevector-u64-native-set!: "incorrect argum
 bytevector.mo:Expected error in mat bytevector-u64-native-set!: "incorrect argument count in call (bytevector-u64-native-set! $v1)".
 bytevector.mo:Expected error in mat bytevector-u64-native-set!: "incorrect argument count in call (bytevector-u64-native-set! $v1 0)".
 bytevector.mo:Expected error in mat bytevector-u64-native-set!: "incorrect argument count in call (bytevector-u64-native-set! $v1 0 0 15)".
-bytevector.mo:Expected error in mat bytevector-u64-native-set!: "bytevector-u64-native-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-u64-native-set!: "bytevector-u64-native-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-u64-native-set!: "bytevector-u64-native-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector-u64-native-set!: "bytevector-u64-native-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-u64-native-set!: "bytevector-u64-native-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-u64-native-set!: "bytevector-u64-native-set!: invalid index 1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-u64-native-set!: "bytevector-u64-native-set!: invalid index 2 for bytevector #vu8(173 173 173 173 173 173 ...)".
@@ -2834,8 +2839,8 @@ bytevector.mo:Expected error in mat bytevector-s64-set!: "incorrect argument cou
 bytevector.mo:Expected error in mat bytevector-s64-set!: "incorrect argument count in call (bytevector-s64-set! $v1 0)".
 bytevector.mo:Expected error in mat bytevector-s64-set!: "incorrect argument count in call (bytevector-s64-set! $v1 0 0)".
 bytevector.mo:Expected error in mat bytevector-s64-set!: "incorrect argument count in call (bytevector-s64-set! $v1 0 0 (quote big) 15)".
-bytevector.mo:Expected error in mat bytevector-s64-set!: "bytevector-s64-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-s64-set!: "bytevector-s64-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-s64-set!: "bytevector-s64-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector-s64-set!: "bytevector-s64-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-s64-set!: "bytevector-s64-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-s64-set!: "bytevector-s64-set!: invalid index <int> for 8-byte field of bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-s64-set!: "bytevector-s64-set!: invalid index <int> for 8-byte field of bytevector #vu8(173 173 173 173 173 173 ...)".
@@ -2857,8 +2862,8 @@ bytevector.mo:Expected error in mat bytevector-u64-set!: "incorrect argument cou
 bytevector.mo:Expected error in mat bytevector-u64-set!: "incorrect argument count in call (bytevector-u64-set! $v1 0)".
 bytevector.mo:Expected error in mat bytevector-u64-set!: "incorrect argument count in call (bytevector-u64-set! $v1 0 0)".
 bytevector.mo:Expected error in mat bytevector-u64-set!: "incorrect argument count in call (bytevector-u64-set! $v1 0 0 (quote big) 15)".
-bytevector.mo:Expected error in mat bytevector-u64-set!: "bytevector-u64-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-u64-set!: "bytevector-u64-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-u64-set!: "bytevector-u64-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector-u64-set!: "bytevector-u64-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-u64-set!: "bytevector-u64-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-u64-set!: "bytevector-u64-set!: invalid index <int> for 8-byte field of bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-u64-set!: "bytevector-u64-set!: invalid index <int> for 8-byte field of bytevector #vu8(173 173 173 173 173 173 ...)".
@@ -2959,8 +2964,8 @@ bytevector.mo:Expected error in mat bytevector-ieee-single-native-set!: "incorre
 bytevector.mo:Expected error in mat bytevector-ieee-single-native-set!: "incorrect argument count in call (bytevector-ieee-single-native-set! $v1)".
 bytevector.mo:Expected error in mat bytevector-ieee-single-native-set!: "incorrect argument count in call (bytevector-ieee-single-native-set! $v1 0)".
 bytevector.mo:Expected error in mat bytevector-ieee-single-native-set!: "incorrect argument count in call (bytevector-ieee-single-native-set! $v1 0 0.0 0.0)".
-bytevector.mo:Expected error in mat bytevector-ieee-single-native-set!: "bytevector-ieee-single-native-set!: #(3 252 5 0 0 0 ...) is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-ieee-single-native-set!: "bytevector-ieee-single-native-set!: #(3 252 5 0 0 0 ...) is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-ieee-single-native-set!: "bytevector-ieee-single-native-set!: #(3 252 5 0 0 0 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector-ieee-single-native-set!: "bytevector-ieee-single-native-set!: #(3 252 5 0 0 0 ...) is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-ieee-single-native-set!: "bytevector-ieee-single-native-set!: invalid index -1 for bytevector #vu8(235 235 235 235 235 235 ...)".
 bytevector.mo:Expected error in mat bytevector-ieee-single-native-set!: "bytevector-ieee-single-native-set!: invalid index 1 for bytevector #vu8(235 235 235 235 235 235 ...)".
 bytevector.mo:Expected error in mat bytevector-ieee-single-native-set!: "bytevector-ieee-single-native-set!: invalid index 2 for bytevector #vu8(235 235 235 235 235 235 ...)".
@@ -2996,8 +3001,8 @@ bytevector.mo:Expected error in mat bytevector-ieee-double-native-set!: "incorre
 bytevector.mo:Expected error in mat bytevector-ieee-double-native-set!: "incorrect argument count in call (bytevector-ieee-double-native-set! $v1)".
 bytevector.mo:Expected error in mat bytevector-ieee-double-native-set!: "incorrect argument count in call (bytevector-ieee-double-native-set! $v1 0)".
 bytevector.mo:Expected error in mat bytevector-ieee-double-native-set!: "incorrect argument count in call (bytevector-ieee-double-native-set! $v1 0 0.0 0.0)".
-bytevector.mo:Expected error in mat bytevector-ieee-double-native-set!: "bytevector-ieee-double-native-set!: #(3 252 5 0 0 0 ...) is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-ieee-double-native-set!: "bytevector-ieee-double-native-set!: #(3 252 5 0 0 0 ...) is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-ieee-double-native-set!: "bytevector-ieee-double-native-set!: #(3 252 5 0 0 0 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector-ieee-double-native-set!: "bytevector-ieee-double-native-set!: #(3 252 5 0 0 0 ...) is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-ieee-double-native-set!: "bytevector-ieee-double-native-set!: invalid index -1 for bytevector #vu8(235 235 235 235 235 235 ...)".
 bytevector.mo:Expected error in mat bytevector-ieee-double-native-set!: "bytevector-ieee-double-native-set!: invalid index 1 for bytevector #vu8(235 235 235 235 235 235 ...)".
 bytevector.mo:Expected error in mat bytevector-ieee-double-native-set!: "bytevector-ieee-double-native-set!: invalid index 2 for bytevector #vu8(235 235 235 235 235 235 ...)".
@@ -3080,8 +3085,8 @@ bytevector.mo:Expected error in mat bytevector-ieee-single-set!: "incorrect argu
 bytevector.mo:Expected error in mat bytevector-ieee-single-set!: "incorrect argument count in call (bytevector-ieee-single-set! $v1 0)".
 bytevector.mo:Expected error in mat bytevector-ieee-single-set!: "incorrect argument count in call (bytevector-ieee-single-set! $v1 0 0.0)".
 bytevector.mo:Expected error in mat bytevector-ieee-single-set!: "incorrect argument count in call (bytevector-ieee-single-set! $v1 0 0.0 (quote big) (quote bigger))".
-bytevector.mo:Expected error in mat bytevector-ieee-single-set!: "bytevector-ieee-single-set!: #(3 252 5 0 0 0 ...) is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-ieee-single-set!: "bytevector-ieee-single-set!: #(3 252 5 0 0 0 ...) is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-ieee-single-set!: "bytevector-ieee-single-set!: #(3 252 5 0 0 0 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector-ieee-single-set!: "bytevector-ieee-single-set!: #(3 252 5 0 0 0 ...) is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-ieee-single-set!: "bytevector-ieee-single-set!: invalid index -1 for bytevector #vu8(235 235 235 235 235 235 ...)".
 bytevector.mo:Expected error in mat bytevector-ieee-single-set!: "bytevector-ieee-single-set!: invalid index 36 for 4-byte field of bytevector #vu8(235 235 235 235 235 235 ...)".
 bytevector.mo:Expected error in mat bytevector-ieee-single-set!: "bytevector-ieee-single-set!: invalid index 37 for 4-byte field of bytevector #vu8(235 235 235 235 235 235 ...)".
@@ -3101,8 +3106,8 @@ bytevector.mo:Expected error in mat bytevector-ieee-double-set!: "incorrect argu
 bytevector.mo:Expected error in mat bytevector-ieee-double-set!: "incorrect argument count in call (bytevector-ieee-double-set! $v1 0)".
 bytevector.mo:Expected error in mat bytevector-ieee-double-set!: "incorrect argument count in call (bytevector-ieee-double-set! $v1 0 0.0)".
 bytevector.mo:Expected error in mat bytevector-ieee-double-set!: "incorrect argument count in call (bytevector-ieee-double-set! $v1 0 0.0 (quote big) (quote bigger))".
-bytevector.mo:Expected error in mat bytevector-ieee-double-set!: "bytevector-ieee-double-set!: #(3 252 5 0 0 0 ...) is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-ieee-double-set!: "bytevector-ieee-double-set!: #(3 252 5 0 0 0 ...) is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-ieee-double-set!: "bytevector-ieee-double-set!: #(3 252 5 0 0 0 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector-ieee-double-set!: "bytevector-ieee-double-set!: #(3 252 5 0 0 0 ...) is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-ieee-double-set!: "bytevector-ieee-double-set!: invalid index -1 for bytevector #vu8(235 235 235 235 235 235 ...)".
 bytevector.mo:Expected error in mat bytevector-ieee-double-set!: "bytevector-ieee-double-set!: invalid index <int> for 8-byte field of bytevector #vu8(235 235 235 235 235 235 ...)".
 bytevector.mo:Expected error in mat bytevector-ieee-double-set!: "bytevector-ieee-double-set!: invalid index <int> for 8-byte field of bytevector #vu8(235 235 235 235 235 235 ...)".
@@ -3208,8 +3213,8 @@ bytevector.mo:Expected error in mat bytevector-sint-set!: "incorrect argument co
 bytevector.mo:Expected error in mat bytevector-sint-set!: "incorrect argument count in call (bytevector-sint-set! $v1 0 7)".
 bytevector.mo:Expected error in mat bytevector-sint-set!: "incorrect argument count in call (bytevector-sint-set! $v1 0 7 (quote big))".
 bytevector.mo:Expected error in mat bytevector-sint-set!: "incorrect argument count in call (bytevector-sint-set! $v1 0 7 (quote big) 5 ...)".
-bytevector.mo:Expected error in mat bytevector-sint-set!: "bytevector-sint-set!: #(3 252 5 0 0 0 ...) is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-sint-set!: "bytevector-sint-set!: #(3 252 5 0 0 0 ...) is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-sint-set!: "bytevector-sint-set!: #(3 252 5 0 0 0 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector-sint-set!: "bytevector-sint-set!: #(3 252 5 0 0 0 ...) is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-sint-set!: "bytevector-sint-set!: invalid index -1 for bytevector #vu8(0 0 0 0 0 0 ...)".
 bytevector.mo:Expected error in mat bytevector-sint-set!: "bytevector-sint-set!: invalid index -1 for bytevector #vu8(0 0 0 0 0 0 ...)".
 bytevector.mo:Expected error in mat bytevector-sint-set!: "bytevector-sint-set!: invalid index -1 for bytevector #vu8(0 0 0 0 0 0 ...)".
@@ -3272,8 +3277,8 @@ bytevector.mo:Expected error in mat bytevector-uint-set!: "incorrect argument co
 bytevector.mo:Expected error in mat bytevector-uint-set!: "incorrect argument count in call (bytevector-uint-set! $v1 0 7)".
 bytevector.mo:Expected error in mat bytevector-uint-set!: "incorrect argument count in call (bytevector-uint-set! $v1 0 7 (quote big))".
 bytevector.mo:Expected error in mat bytevector-uint-set!: "incorrect argument count in call (bytevector-uint-set! $v1 0 7 (quote big) 5 ...)".
-bytevector.mo:Expected error in mat bytevector-uint-set!: "bytevector-uint-set!: #(3 252 5 0 0 0 ...) is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-uint-set!: "bytevector-uint-set!: #(3 252 5 0 0 0 ...) is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-uint-set!: "bytevector-uint-set!: #(3 252 5 0 0 0 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector-uint-set!: "bytevector-uint-set!: #(3 252 5 0 0 0 ...) is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-uint-set!: "bytevector-uint-set!: invalid index -1 for bytevector #vu8(0 0 0 0 0 0 ...)".
 bytevector.mo:Expected error in mat bytevector-uint-set!: "bytevector-uint-set!: invalid index -1 for bytevector #vu8(0 0 0 0 0 0 ...)".
 bytevector.mo:Expected error in mat bytevector-uint-set!: "bytevector-uint-set!: invalid index -1 for bytevector #vu8(0 0 0 0 0 0 ...)".
@@ -3341,7 +3346,7 @@ bytevector.mo:Expected error in mat bytevector-copy!: "incorrect argument count
 bytevector.mo:Expected error in mat bytevector-copy!: "incorrect argument count in call (bytevector-copy! $v2 3 $v1 1)".
 bytevector.mo:Expected error in mat bytevector-copy!: "incorrect argument count in call (bytevector-copy! $v2 3 $v1 1 2 ...)".
 bytevector.mo:Expected error in mat bytevector-copy!: "bytevector-copy!: 0 is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-copy!: "bytevector-copy!: #(1 2 3) is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-copy!: "bytevector-copy!: #(1 2 3) is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-copy!: "bytevector-copy!: invalid start value -1".
 bytevector.mo:Expected error in mat bytevector-copy!: "bytevector-copy!: invalid start value -1".
 bytevector.mo:Expected error in mat bytevector-copy!: "bytevector-copy!: invalid start value a".
@@ -3366,8 +3371,8 @@ bytevector.mo:Expected error in mat bytevector-copy!: "bytevector-copy!: index 5
 bytevector.mo:Expected error in mat bytevector-truncate!: "incorrect argument count in call (bytevector-truncate!)".
 bytevector.mo:Expected error in mat bytevector-truncate!: "incorrect argument count in call (bytevector-truncate! $v)".
 bytevector.mo:Expected error in mat bytevector-truncate!: "incorrect argument count in call (bytevector-truncate! $v 3 15)".
-bytevector.mo:Expected error in mat bytevector-truncate!: "bytevector-truncate!: 0 is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-truncate!: "bytevector-truncate!: "abc" is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-truncate!: "bytevector-truncate!: 0 is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector-truncate!: "bytevector-truncate!: "abc" is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-truncate!: "bytevector-truncate!: invalid new length -1 for #vu8(1 2 3 4 5 6 ...)".
 bytevector.mo:Expected error in mat bytevector-truncate!: "bytevector-truncate!: invalid new length 10 for #vu8(1 2 3 4 5 6 ...)".
 bytevector.mo:Expected error in mat bytevector-truncate!: "bytevector-truncate!: invalid new length 1000 for #vu8(1 2 3 4 5 6 ...)".
@@ -3376,8 +3381,8 @@ bytevector.mo:Expected error in mat bytevector-truncate!: "bytevector-truncate!:
 bytevector.mo:Expected error in mat bytevector-fill!: "incorrect argument count in call (bytevector-fill!)".
 bytevector.mo:Expected error in mat bytevector-fill!: "incorrect argument count in call (bytevector-fill! $v1)".
 bytevector.mo:Expected error in mat bytevector-fill!: "incorrect argument count in call (bytevector-fill! $v1 0 0)".
-bytevector.mo:Expected error in mat bytevector-fill!: "bytevector-fill!: a is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-fill!: "bytevector-fill!: #(1) is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-fill!: "bytevector-fill!: a is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector-fill!: "bytevector-fill!: #(1) is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-fill!: "bytevector-fill!: -129 is not a valid fill value".
 bytevector.mo:Expected error in mat bytevector-fill!: "bytevector-fill!: 256 is not a valid fill value".
 bytevector.mo:Expected error in mat bytevector-fill!: "bytevector-fill!: a is not a valid fill value".
@@ -3537,6 +3542,37 @@ bytevector.mo:Expected error in mat bytevector=?: "incorrect argument count in c
 bytevector.mo:Expected error in mat bytevector=?: "bytevector=?: a is not a bytevector".
 bytevector.mo:Expected error in mat bytevector=?: "bytevector=?: "a" is not a bytevector".
 bytevector.mo:Expected error in mat tspl/csug-examples: "invalid endianness "spam"".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-uint-set!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-sint-set!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-u8-set!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-s8-set!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-u16-set!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-s16-set!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-u16-native-set!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-s16-native-set!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-u24-set!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-s24-set!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-u32-set!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-s32-set!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-u32-native-set!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-s32-native-set!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-u40-set!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-s40-set!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-u48-set!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-s48-set!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-u56-set!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-s56-set!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-u64-set!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-s64-set!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-u64-native-set!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-s64-native-set!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-ieee-single-set!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-ieee-double-set!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-ieee-single-native-set!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-ieee-double-native-set!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-fill!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-copy!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-truncate!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
 misc.mo:Expected error in mat compiler1: "variable i-am-not-bound is not bound".
 misc.mo:Expected error in mat compiler1: "attempt to apply non-procedure oops".
 misc.mo:Expected error in mat compiler1: "incorrect argument count in call (g (list))".
@@ -3751,7 +3787,7 @@ cp0.mo:Expected error in mat expand-output: "expand-output: #t is not a textual
 cp0.mo:Expected error in mat expand-output: "expand-output: #<binary output port bytevector> is not a textual output port or #f".
 cp0.mo:Expected error in mat expand/optimize-output: "expand/optimize-output: #t is not a textual output port or #f".
 cp0.mo:Expected error in mat expand/optimize-output: "expand/optimize-output: #<binary output port bytevector> is not a textual output port or #f".
-5_6.mo:Expected error in mat make-vector: "make-vector: a is not a nonnegative fixnum".
+5_6.mo:Expected error in mat make-vector: "make-vector: a is not a valid vector length".
 5_6.mo:Expected error in mat vector-length: "vector-length: (a b c) is not a vector".
 5_6.mo:Expected error in mat vector-ref: "vector-ref: 3 is not a valid index for #(a b c)".
 5_6.mo:Expected error in mat vector-ref: "vector-ref: -1 is not a valid index for #(a b c)".
@@ -3760,16 +3796,16 @@ cp0.mo:Expected error in mat expand/optimize-output: "expand/optimize-output: #<
 5_6.mo:Expected error in mat vector-set!: "vector-set!: 3 is not a valid index for #(a b c)".
 5_6.mo:Expected error in mat vector-set!: "vector-set!: -1 is not a valid index for #(a b c)".
 5_6.mo:Expected error in mat vector-set!: "vector-set!: a is not a valid index for #(a b c)".
-5_6.mo:Expected error in mat vector-set!: "vector-set!: (a b c) is not a vector".
+5_6.mo:Expected error in mat vector-set!: "vector-set!: (a b c) is not a mutable vector".
 5_6.mo:Expected error in mat vector-set-fixnum!: "vector-set-fixnum!: 3 is not a valid index for #(a b c)".
 5_6.mo:Expected error in mat vector-set-fixnum!: "vector-set-fixnum!: -1 is not a valid index for #(a b c)".
 5_6.mo:Expected error in mat vector-set-fixnum!: "vector-set-fixnum!: a is not a valid index for #(a b c)".
-5_6.mo:Expected error in mat vector-set-fixnum!: "vector-set-fixnum!: (a b c) is not a vector".
+5_6.mo:Expected error in mat vector-set-fixnum!: "vector-set-fixnum!: (a b c) is not a mutable vector".
 5_6.mo:Expected error in mat vector-set-fixnum!: "vector-set-fixnum!: d is not a fixnum".
 5_6.mo:Expected error in mat vector-set-fixnum!: "vector-set-fixnum!: #\d is not a fixnum".
 5_6.mo:Expected error in mat vector-set-fixnum!: "vector-set-fixnum!: (a b c) is not a fixnum".
 5_6.mo:Expected error in mat vector-copy: "vector-copy: (a b c) is not a vector".
-5_6.mo:Expected error in mat vector-fill!: "vector-fill!: #vfx() is not a vector".
+5_6.mo:Expected error in mat vector-fill!: "vector-fill!: #vfx() is not a mutable vector".
 5_6.mo:Expected error in mat list->vector: "list->vector: #(a b c) is not a proper list".
 5_6.mo:Expected error in mat list->vector: "list->vector: (#\a #\b . #\c) is not a proper list".
 5_6.mo:Expected error in mat list->vector: "list->vector: (#\a #\b #\c #\b #\c #\b ...) is circular".
@@ -3790,11 +3826,11 @@ cp0.mo:Expected error in mat expand/optimize-output: "expand/optimize-output: #<
 5_6.mo:Expected error in mat fxvector-set!: "fxvector-set!: -1 is not a valid index for #vfx(3 4 5)".
 5_6.mo:Expected error in mat fxvector-set!: "fxvector-set!: a is not a valid index for #vfx(3 4 5)".
 5_6.mo:Expected error in mat fxvector-set!: "fxvector-set!: d is not a fixnum".
-5_6.mo:Expected error in mat fxvector-set!: "fxvector-set!: (3 4 5) is not an fxvector".
+5_6.mo:Expected error in mat fxvector-set!: "fxvector-set!: (3 4 5) is not a mutable fxvector".
 5_6.mo:Expected error in mat fxvector-set!: "fxvector-set!: <-int> is not a fixnum".
 5_6.mo:Expected error in mat fxvector-set!: "fxvector-set!: <int> is not a fixnum".
-5_6.mo:Expected error in mat fxvector-set!: "fxvector-set!: (3 4 5) is not an fxvector".
-5_6.mo:Expected error in mat fxvector-set!: "fxvector-set!: #(3 4) is not an fxvector".
+5_6.mo:Expected error in mat fxvector-set!: "fxvector-set!: (3 4 5) is not a mutable fxvector".
+5_6.mo:Expected error in mat fxvector-set!: "fxvector-set!: #(3 4) is not a mutable fxvector".
 5_6.mo:Expected error in mat fxvector-set!: "fxvector-set!: 3 is not a valid index for #vfx(3 4 5)".
 5_6.mo:Expected error in mat fxvector-set!: "fxvector-set!: -3 is not a valid index for #vfx(3 4 5)".
 5_6.mo:Expected error in mat fxvector-set!: "fxvector-set!: <int> is not a valid index for #vfx(3 4 5)".
@@ -3805,7 +3841,7 @@ cp0.mo:Expected error in mat expand/optimize-output: "expand/optimize-output: #<
 5_6.mo:Expected error in mat fxvector-set!: "fxvector-set!: a is not a fixnum".
 5_6.mo:Expected error in mat fxvector-copy: "fxvector-copy: (a b c) is not an fxvector".
 5_6.mo:Expected error in mat fxvector-fill!: "fxvector-fill!: a is not a fixnum".
-5_6.mo:Expected error in mat fxvector-fill!: "fxvector-fill!: #(1) is not an fxvector".
+5_6.mo:Expected error in mat fxvector-fill!: "fxvector-fill!: #(1) is not a mutable fxvector".
 5_6.mo:Expected error in mat list->fxvector: "list->fxvector: #(a b c) is not a proper list".
 5_6.mo:Expected error in mat list->fxvector: "list->fxvector: (1 2 . 3) is not a proper list".
 5_6.mo:Expected error in mat list->fxvector: "list->fxvector: (1 2 3 2 3 2 ...) is circular".
@@ -3856,10 +3892,16 @@ cp0.mo:Expected error in mat expand/optimize-output: "expand/optimize-output: #<
 5_6.mo:Expected error in mat vector-sort!: "incorrect argument count in call (vector-sort! >)".
 5_6.mo:Expected error in mat vector-sort!: "incorrect argument count in call (vector-sort! (quote #(a b c)))".
 5_6.mo:Expected error in mat vector-sort!: "incorrect argument count in call (vector-sort! > (quote #(1 2 3)) #t)".
-5_6.mo:Expected error in mat vector-sort!: "vector-sort!: 3 is not a vector".
-5_6.mo:Expected error in mat vector-sort!: "vector-sort!: (1 2 3) is not a vector".
+5_6.mo:Expected error in mat vector-sort!: "vector-sort!: 3 is not a mutable vector".
+5_6.mo:Expected error in mat vector-sort!: "vector-sort!: (1 2 3) is not a mutable vector".
 5_6.mo:Expected error in mat vector-sort!: "vector-sort!: #(a b c) is not a procedure".
 5_6.mo:Expected error in mat vector-sort!: ">: b is not a real number".
+5_6.mo:Expected error in mat vector->immutable-vector: "vector-set!: #(1 2 3) is not a mutable vector".
+5_6.mo:Expected error in mat vector->immutable-vector: "vector-set-fixnum!: #(1 2 3) is not a mutable vector".
+5_6.mo:Expected error in mat vector->immutable-vector: "vector-fill!: #(1 2 3) is not a mutable vector".
+5_6.mo:Expected error in mat vector->immutable-vector: "vector-sort!: #(1 2 3) is not a mutable vector".
+5_6.mo:Expected error in mat fxvector->immutable-fxvector: "fxvector-set!: #vfx(1 2 3) is not a mutable fxvector".
+5_6.mo:Expected error in mat fxvector->immutable-fxvector: "fxvector-fill!: #vfx(1 2 3) is not a mutable fxvector".
 5_7.mo:Expected error in mat string->symbol: "string->symbol: 3 is not a string".
 5_7.mo:Expected error in mat string->symbol: "string->symbol: a is not a string".
 5_7.mo:Expected error in mat gensym: "gensym: #(a b c) is not a string".
diff --git a/mats/root-experr-compile-2-f-f-f b/mats/root-experr-compile-2-f-f-f
index 6cf94a74a7..456c44da9a 100644
--- a/mats/root-experr-compile-2-f-f-f
+++ b/mats/root-experr-compile-2-f-f-f
@@ -243,7 +243,9 @@ primvars.mo:Expected error in mat trace-output-port: "trace-output-port: #<input
 4.mo:Expected error in mat apply: "apply: (1 2 1 2 1 2 ...) is circular".
 4.mo:Expected error in mat begin: "invalid syntax (begin)".
 4.mo:Expected error in mat cond: "invalid syntax x".
+4.mo:Expected error in mat exclusive-cond: "invalid exclusive-cond clause (a . b)".
 4.mo:Expected error in mat exclusive-cond: "invalid syntax x".
+4.mo:Expected error in mat case: "invalid case clause (a . b)".
 4.mo:Expected error in mat r6rs:case: "invalid syntax (r6rs:case (quote a) (a (quote yes)) (b (quote no)))".
 4.mo:Expected error in mat r6rs:case: "invalid syntax (case (quote a) (a (quote yes)) (b (quote no)))".
 4.mo:Expected error in mat named-let: "incorrect argument count in call ((letrec ((...)) x) 3 4)".
@@ -1966,7 +1968,7 @@ primvars.mo:Expected error in mat trace-output-port: "trace-output-port: #<input
 5_5.mo:Expected error in mat make-string: "incorrect argument count in call (make-string)".
 5_5.mo:Expected error in mat make-string: "incorrect argument count in call (make-string 2 #\a #\b)".
 5_5.mo:Expected error in mat make-string: "make-string: a is not a character".
-5_5.mo:Expected error in mat make-string: "make-string: a is not a nonnegative fixnum".
+5_5.mo:Expected error in mat make-string: "make-string: a is not a valid string length".
 5_5.mo:Expected error in mat string-length: "incorrect argument count in call (string-length)".
 5_5.mo:Expected error in mat string-length: "incorrect argument count in call (string-length "hi" "there")".
 5_5.mo:Expected error in mat string-length: "string-length: a is not a string".
@@ -1981,7 +1983,7 @@ primvars.mo:Expected error in mat trace-output-port: "trace-output-port: #<input
 5_5.mo:Expected error in mat string-set!: "incorrect argument count in call (string-set! "hi")".
 5_5.mo:Expected error in mat string-set!: "incorrect argument count in call (string-set! "hi" 1)".
 5_5.mo:Expected error in mat string-set!: "incorrect argument count in call (string-set! "hi" 3 #\a #\b)".
-5_5.mo:Expected error in mat string-set!: "string-set!: a is not a string".
+5_5.mo:Expected error in mat string-set!: "string-set!: a is not a mutable string".
 5_5.mo:Expected error in mat string-set!: "string-set!: a is not a valid index for "hi"".
 5_5.mo:Expected error in mat string-set!: "string-set!: 3 is not a valid index for "hi"".
 5_5.mo:Expected error in mat string-set!: "string-set!: -1 is not a valid index for "hi"".
@@ -1997,7 +1999,7 @@ primvars.mo:Expected error in mat trace-output-port: "trace-output-port: #<input
 5_5.mo:Expected error in mat string-copy!: "incorrect argument count in call (string-copy! $s2 3 $s1 1)".
 5_5.mo:Expected error in mat string-copy!: "incorrect argument count in call (string-copy! $s2 3 $s1 1 2 ...)".
 5_5.mo:Expected error in mat string-copy!: "string-copy!: 0 is not a string".
-5_5.mo:Expected error in mat string-copy!: "string-copy!: #vu8(1 2 3) is not a string".
+5_5.mo:Expected error in mat string-copy!: "string-copy!: #vu8(1 2 3) is not a mutable string".
 5_5.mo:Expected error in mat string-copy!: "string-copy!: invalid start value -1".
 5_5.mo:Expected error in mat string-copy!: "string-copy!: invalid start value -1".
 5_5.mo:Expected error in mat string-copy!: "string-copy!: invalid start value a".
@@ -2022,8 +2024,8 @@ primvars.mo:Expected error in mat trace-output-port: "trace-output-port: #<input
 5_5.mo:Expected error in mat string-truncate!: "incorrect argument count in call (string-truncate!)".
 5_5.mo:Expected error in mat string-truncate!: "incorrect argument count in call (string-truncate! $s)".
 5_5.mo:Expected error in mat string-truncate!: "incorrect argument count in call (string-truncate! $s 3 15)".
-5_5.mo:Expected error in mat string-truncate!: "string-truncate!: 0 is not a string".
-5_5.mo:Expected error in mat string-truncate!: "string-truncate!: #vu8(1 2 3) is not a string".
+5_5.mo:Expected error in mat string-truncate!: "string-truncate!: 0 is not a mutable string".
+5_5.mo:Expected error in mat string-truncate!: "string-truncate!: #vu8(1 2 3) is not a mutable string".
 5_5.mo:Expected error in mat string-truncate!: "string-truncate!: invalid new length -1 for "abcdefghi"".
 5_5.mo:Expected error in mat string-truncate!: "string-truncate!: invalid new length 10 for "abcdefghi"".
 5_5.mo:Expected error in mat string-truncate!: "string-truncate!: invalid new length 1000 for "abcdefghi"".
@@ -2047,14 +2049,14 @@ primvars.mo:Expected error in mat trace-output-port: "trace-output-port: #<input
 5_5.mo:Expected error in mat string-fill!: "incorrect argument count in call (string-fill! "hi")".
 5_5.mo:Expected error in mat string-fill!: "incorrect argument count in call (string-fill! "hi" #\a #\b)".
 5_5.mo:Expected error in mat string-fill!: "string-fill!: a is not a character".
-5_5.mo:Expected error in mat string-fill!: "string-fill!: a is not a string".
+5_5.mo:Expected error in mat string-fill!: "string-fill!: a is not a mutable string".
 5_5.mo:Expected error in mat substring-fill!: "incorrect argument count in call (substring-fill!)".
 5_5.mo:Expected error in mat substring-fill!: "incorrect argument count in call (substring-fill! "hi")".
 5_5.mo:Expected error in mat substring-fill!: "incorrect argument count in call (substring-fill! "hi" 0)".
 5_5.mo:Expected error in mat substring-fill!: "incorrect argument count in call (substring-fill! "hi" 0 2)".
 5_5.mo:Expected error in mat substring-fill!: "substring-fill!: 0 and 3 are not valid start/end indices for "hi"".
 5_5.mo:Expected error in mat substring-fill!: "substring-fill!: -1 and 3 are not valid start/end indices for "hi"".
-5_5.mo:Expected error in mat substring-fill!: "substring-fill!: a is not a string".
+5_5.mo:Expected error in mat substring-fill!: "substring-fill!: a is not a mutable string".
 5_5.mo:Expected error in mat substring-fill!: "substring-fill!: 0 and a are not valid start/end indices for "hi"".
 5_5.mo:Expected error in mat substring-fill!: "substring-fill!: 1 and 0 are not valid start/end indices for "hi"".
 5_5.mo:Expected error in mat list->string: "incorrect argument count in call (list->string)".
@@ -2066,6 +2068,11 @@ primvars.mo:Expected error in mat trace-output-port: "trace-output-port: #<input
 5_5.mo:Expected error in mat string->list: "incorrect argument count in call (string->list)".
 5_5.mo:Expected error in mat string->list: "incorrect argument count in call (string->list "ab" "cd")".
 5_5.mo:Expected error in mat string->list: "string->list: a is not a string".
+5_5.mo:Expected error in mat string->immutable-string: "string-set!: "abc" is not a mutable string".
+5_5.mo:Expected error in mat string->immutable-string: "string-fill!: "abc" is not a mutable string".
+5_5.mo:Expected error in mat string->immutable-string: "substring-fill!: "abc" is not a mutable string".
+5_5.mo:Expected error in mat string->immutable-string: "string-copy!: "abc" is not a mutable string".
+5_5.mo:Expected error in mat string->immutable-string: "string-truncate!: "abc" is not a mutable string".
 bytevector.mo:Expected error in mat native-endianness: "incorrect argument count in call (native-endianness (quote big))".
 bytevector.mo:Expected error in mat endianness: "invalid endianness spam".
 bytevector.mo:Expected error in mat endianness: "invalid endianness (quote big)".
@@ -2075,11 +2082,11 @@ bytevector.mo:Expected error in mat endianness: "invalid syntax (endianness . bi
 bytevector.mo:Expected error in mat endianness: "invalid syntax (endianness big little)".
 bytevector.mo:Expected error in mat make-bytevector: "incorrect argument count in call (make-bytevector)".
 bytevector.mo:Expected error in mat make-bytevector: "incorrect argument count in call (make-bytevector 0 0 0)".
-bytevector.mo:Expected error in mat make-bytevector: "make-bytevector: -1 is not a nonnegative fixnum".
-bytevector.mo:Expected error in mat make-bytevector: "make-bytevector: -1 is not a nonnegative fixnum".
-bytevector.mo:Expected error in mat make-bytevector: "make-bytevector: <int> is not a nonnegative fixnum".
-bytevector.mo:Expected error in mat make-bytevector: "make-bytevector: <int> is not a nonnegative fixnum".
-bytevector.mo:Expected error in mat make-bytevector: "make-bytevector: a is not a nonnegative fixnum".
+bytevector.mo:Expected error in mat make-bytevector: "make-bytevector: -1 is not a valid bytevector length".
+bytevector.mo:Expected error in mat make-bytevector: "make-bytevector: -1 is not a valid bytevector length".
+bytevector.mo:Expected error in mat make-bytevector: "make-bytevector: <int> is not a valid bytevector length".
+bytevector.mo:Expected error in mat make-bytevector: "make-bytevector: <int> is not a valid bytevector length".
+bytevector.mo:Expected error in mat make-bytevector: "make-bytevector: a is not a valid bytevector length".
 bytevector.mo:Expected error in mat make-bytevector: "make-bytevector: a is not a valid fill value".
 bytevector.mo:Expected error in mat make-bytevector: "make-bytevector: 256 is not a valid fill value".
 bytevector.mo:Expected error in mat make-bytevector: "make-bytevector: -129 is not a valid fill value".
@@ -2115,8 +2122,8 @@ bytevector.mo:Expected error in mat bytevector-s8-set!: "incorrect argument coun
 bytevector.mo:Expected error in mat bytevector-s8-set!: "incorrect argument count in call (bytevector-s8-set! $v1)".
 bytevector.mo:Expected error in mat bytevector-s8-set!: "incorrect argument count in call (bytevector-s8-set! $v1 2)".
 bytevector.mo:Expected error in mat bytevector-s8-set!: "incorrect argument count in call (bytevector-s8-set! $v1 2 3 4)".
-bytevector.mo:Expected error in mat bytevector-s8-set!: "bytevector-s8-set!: (3 4 5) is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-s8-set!: "bytevector-s8-set!: (3 4 5) is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-s8-set!: "bytevector-s8-set!: (3 4 5) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector-s8-set!: "bytevector-s8-set!: (3 4 5) is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-s8-set!: "bytevector-s8-set!: 3 is not a valid index for #vu8(3 4 5)".
 bytevector.mo:Expected error in mat bytevector-s8-set!: "bytevector-s8-set!: -1 is not a valid index for #vu8(3 4 5)".
 bytevector.mo:Expected error in mat bytevector-s8-set!: "bytevector-s8-set!: a is not a valid index for #vu8(3 4 5)".
@@ -2127,8 +2134,8 @@ bytevector.mo:Expected error in mat bytevector-u8-set!: "incorrect argument coun
 bytevector.mo:Expected error in mat bytevector-u8-set!: "incorrect argument count in call (bytevector-u8-set! $v1)".
 bytevector.mo:Expected error in mat bytevector-u8-set!: "incorrect argument count in call (bytevector-u8-set! $v1 2)".
 bytevector.mo:Expected error in mat bytevector-u8-set!: "incorrect argument count in call (bytevector-u8-set! $v1 2 3 4)".
-bytevector.mo:Expected error in mat bytevector-u8-set!: "bytevector-u8-set!: (3 4 5) is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-u8-set!: "bytevector-u8-set!: (3 4 5) is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-u8-set!: "bytevector-u8-set!: (3 4 5) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector-u8-set!: "bytevector-u8-set!: (3 4 5) is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-u8-set!: "bytevector-u8-set!: 3 is not a valid index for #vu8(3 4 5)".
 bytevector.mo:Expected error in mat bytevector-u8-set!: "bytevector-u8-set!: -1 is not a valid index for #vu8(3 4 5)".
 bytevector.mo:Expected error in mat bytevector-u8-set!: "bytevector-u8-set!: a is not a valid index for #vu8(3 4 5)".
@@ -2159,8 +2166,8 @@ bytevector.mo:Expected error in mat bytevector-s16-native-set!: "incorrect argum
 bytevector.mo:Expected error in mat bytevector-s16-native-set!: "incorrect argument count in call (bytevector-s16-native-set! $v1)".
 bytevector.mo:Expected error in mat bytevector-s16-native-set!: "incorrect argument count in call (bytevector-s16-native-set! $v1 0)".
 bytevector.mo:Expected error in mat bytevector-s16-native-set!: "incorrect argument count in call (bytevector-s16-native-set! $v1 0 0 15)".
-bytevector.mo:Expected error in mat bytevector-s16-native-set!: "bytevector-s16-native-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-s16-native-set!: "bytevector-s16-native-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-s16-native-set!: "bytevector-s16-native-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector-s16-native-set!: "bytevector-s16-native-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-s16-native-set!: "bytevector-s16-native-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-s16-native-set!: "bytevector-s16-native-set!: invalid index 1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-s16-native-set!: "bytevector-s16-native-set!: invalid index 3 for bytevector #vu8(173 173 173 173 173 173 ...)".
@@ -2176,8 +2183,8 @@ bytevector.mo:Expected error in mat bytevector-u16-native-set!: "incorrect argum
 bytevector.mo:Expected error in mat bytevector-u16-native-set!: "incorrect argument count in call (bytevector-u16-native-set! $v1)".
 bytevector.mo:Expected error in mat bytevector-u16-native-set!: "incorrect argument count in call (bytevector-u16-native-set! $v1 0)".
 bytevector.mo:Expected error in mat bytevector-u16-native-set!: "incorrect argument count in call (bytevector-u16-native-set! $v1 0 0 15)".
-bytevector.mo:Expected error in mat bytevector-u16-native-set!: "bytevector-u16-native-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-u16-native-set!: "bytevector-u16-native-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-u16-native-set!: "bytevector-u16-native-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector-u16-native-set!: "bytevector-u16-native-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-u16-native-set!: "bytevector-u16-native-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-u16-native-set!: "bytevector-u16-native-set!: invalid index 1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-u16-native-set!: "bytevector-u16-native-set!: invalid index 3 for bytevector #vu8(173 173 173 173 173 173 ...)".
@@ -2217,8 +2224,8 @@ bytevector.mo:Expected error in mat bytevector-s16-set!: "incorrect argument cou
 bytevector.mo:Expected error in mat bytevector-s16-set!: "incorrect argument count in call (bytevector-s16-set! $v1)".
 bytevector.mo:Expected error in mat bytevector-s16-set!: "incorrect argument count in call (bytevector-s16-set! $v1 0 0)".
 bytevector.mo:Expected error in mat bytevector-s16-set!: "incorrect argument count in call (bytevector-s16-set! $v1 0 0 0 (native-endianness))".
-bytevector.mo:Expected error in mat bytevector-s16-set!: "bytevector-s16-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-s16-set!: "bytevector-s16-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-s16-set!: "bytevector-s16-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector-s16-set!: "bytevector-s16-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-s16-set!: "bytevector-s16-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-s16-set!: "bytevector-s16-set!: invalid index 10 for 2-byte field of bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-s16-set!: "bytevector-s16-set!: invalid index 11 for bytevector #vu8(173 173 173 173 173 173 ...)".
@@ -2236,8 +2243,8 @@ bytevector.mo:Expected error in mat bytevector-u16-set!: "incorrect argument cou
 bytevector.mo:Expected error in mat bytevector-u16-set!: "incorrect argument count in call (bytevector-u16-set! $v1)".
 bytevector.mo:Expected error in mat bytevector-u16-set!: "incorrect argument count in call (bytevector-u16-set! $v1 0 0)".
 bytevector.mo:Expected error in mat bytevector-u16-set!: "incorrect argument count in call (bytevector-u16-set! $v1 0 0 0 (native-endianness))".
-bytevector.mo:Expected error in mat bytevector-u16-set!: "bytevector-u16-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-u16-set!: "bytevector-u16-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-u16-set!: "bytevector-u16-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector-u16-set!: "bytevector-u16-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-u16-set!: "bytevector-u16-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-u16-set!: "bytevector-u16-set!: invalid index 10 for 2-byte field of bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-u16-set!: "bytevector-u16-set!: invalid index 11 for bytevector #vu8(173 173 173 173 173 173 ...)".
@@ -2282,8 +2289,8 @@ bytevector.mo:Expected error in mat bytevector-s24-set!: "incorrect argument cou
 bytevector.mo:Expected error in mat bytevector-s24-set!: "incorrect argument count in call (bytevector-s24-set! $v1 0)".
 bytevector.mo:Expected error in mat bytevector-s24-set!: "incorrect argument count in call (bytevector-s24-set! $v1 0 0)".
 bytevector.mo:Expected error in mat bytevector-s24-set!: "incorrect argument count in call (bytevector-s24-set! $v1 0 0 (quote big) 0)".
-bytevector.mo:Expected error in mat bytevector-s24-set!: "bytevector-s24-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-s24-set!: "bytevector-s24-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-s24-set!: "bytevector-s24-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector-s24-set!: "bytevector-s24-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-s24-set!: "bytevector-s24-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-s24-set!: "bytevector-s24-set!: invalid index 21 for 3-byte field of bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-s24-set!: "bytevector-s24-set!: invalid index 22 for 3-byte field of bytevector #vu8(173 173 173 173 173 173 ...)".
@@ -2300,8 +2307,8 @@ bytevector.mo:Expected error in mat bytevector-u24-set!: "incorrect argument cou
 bytevector.mo:Expected error in mat bytevector-u24-set!: "incorrect argument count in call (bytevector-u24-set! $v1 0)".
 bytevector.mo:Expected error in mat bytevector-u24-set!: "incorrect argument count in call (bytevector-u24-set! $v1 0 0)".
 bytevector.mo:Expected error in mat bytevector-u24-set!: "incorrect argument count in call (bytevector-u24-set! $v1 0 0 (quote big) 0)".
-bytevector.mo:Expected error in mat bytevector-u24-set!: "bytevector-u24-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-u24-set!: "bytevector-u24-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-u24-set!: "bytevector-u24-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector-u24-set!: "bytevector-u24-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-u24-set!: "bytevector-u24-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-u24-set!: "bytevector-u24-set!: invalid index 21 for 3-byte field of bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-u24-set!: "bytevector-u24-set!: invalid index 22 for 3-byte field of bytevector #vu8(173 173 173 173 173 173 ...)".
@@ -2345,8 +2352,8 @@ bytevector.mo:Expected error in mat bytevector-s32-native-set!: "incorrect argum
 bytevector.mo:Expected error in mat bytevector-s32-native-set!: "incorrect argument count in call (bytevector-s32-native-set! $v1)".
 bytevector.mo:Expected error in mat bytevector-s32-native-set!: "incorrect argument count in call (bytevector-s32-native-set! $v1 0)".
 bytevector.mo:Expected error in mat bytevector-s32-native-set!: "incorrect argument count in call (bytevector-s32-native-set! $v1 0 0 15)".
-bytevector.mo:Expected error in mat bytevector-s32-native-set!: "bytevector-s32-native-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-s32-native-set!: "bytevector-s32-native-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-s32-native-set!: "bytevector-s32-native-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector-s32-native-set!: "bytevector-s32-native-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-s32-native-set!: "bytevector-s32-native-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-s32-native-set!: "bytevector-s32-native-set!: invalid index 1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-s32-native-set!: "bytevector-s32-native-set!: invalid index 2 for bytevector #vu8(173 173 173 173 173 173 ...)".
@@ -2375,8 +2382,8 @@ bytevector.mo:Expected error in mat bytevector-u32-native-set!: "incorrect argum
 bytevector.mo:Expected error in mat bytevector-u32-native-set!: "incorrect argument count in call (bytevector-u32-native-set! $v1)".
 bytevector.mo:Expected error in mat bytevector-u32-native-set!: "incorrect argument count in call (bytevector-u32-native-set! $v1 0)".
 bytevector.mo:Expected error in mat bytevector-u32-native-set!: "incorrect argument count in call (bytevector-u32-native-set! $v1 0 0 15)".
-bytevector.mo:Expected error in mat bytevector-u32-native-set!: "bytevector-u32-native-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-u32-native-set!: "bytevector-u32-native-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-u32-native-set!: "bytevector-u32-native-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector-u32-native-set!: "bytevector-u32-native-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-u32-native-set!: "bytevector-u32-native-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-u32-native-set!: "bytevector-u32-native-set!: invalid index 1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-u32-native-set!: "bytevector-u32-native-set!: invalid index 2 for bytevector #vu8(173 173 173 173 173 173 ...)".
@@ -2432,8 +2439,8 @@ bytevector.mo:Expected error in mat bytevector-s32-set!: "incorrect argument cou
 bytevector.mo:Expected error in mat bytevector-s32-set!: "incorrect argument count in call (bytevector-s32-set! $v1 0)".
 bytevector.mo:Expected error in mat bytevector-s32-set!: "incorrect argument count in call (bytevector-s32-set! $v1 0 0)".
 bytevector.mo:Expected error in mat bytevector-s32-set!: "incorrect argument count in call (bytevector-s32-set! $v1 0 0 (quote big) 0)".
-bytevector.mo:Expected error in mat bytevector-s32-set!: "bytevector-s32-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-s32-set!: "bytevector-s32-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-s32-set!: "bytevector-s32-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector-s32-set!: "bytevector-s32-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-s32-set!: "bytevector-s32-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-s32-set!: "bytevector-s32-set!: invalid index 20 for 4-byte field of bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-s32-set!: "bytevector-s32-set!: invalid index 21 for 4-byte field of bytevector #vu8(173 173 173 173 173 173 ...)".
@@ -2451,8 +2458,8 @@ bytevector.mo:Expected error in mat bytevector-u32-set!: "incorrect argument cou
 bytevector.mo:Expected error in mat bytevector-u32-set!: "incorrect argument count in call (bytevector-u32-set! $v1 0)".
 bytevector.mo:Expected error in mat bytevector-u32-set!: "incorrect argument count in call (bytevector-u32-set! $v1 0 0)".
 bytevector.mo:Expected error in mat bytevector-u32-set!: "incorrect argument count in call (bytevector-u32-set! $v1 0 0 (quote big) 0)".
-bytevector.mo:Expected error in mat bytevector-u32-set!: "bytevector-u32-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-u32-set!: "bytevector-u32-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-u32-set!: "bytevector-u32-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector-u32-set!: "bytevector-u32-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-u32-set!: "bytevector-u32-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-u32-set!: "bytevector-u32-set!: invalid index 20 for 4-byte field of bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-u32-set!: "bytevector-u32-set!: invalid index 21 for 4-byte field of bytevector #vu8(173 173 173 173 173 173 ...)".
@@ -2496,8 +2503,8 @@ bytevector.mo:Expected error in mat bytevector-s40-set!: "incorrect argument cou
 bytevector.mo:Expected error in mat bytevector-s40-set!: "incorrect argument count in call (bytevector-s40-set! $v1 0)".
 bytevector.mo:Expected error in mat bytevector-s40-set!: "incorrect argument count in call (bytevector-s40-set! $v1 0 0)".
 bytevector.mo:Expected error in mat bytevector-s40-set!: "incorrect argument count in call (bytevector-s40-set! $v1 0 0 (quote big) 0)".
-bytevector.mo:Expected error in mat bytevector-s40-set!: "bytevector-s40-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-s40-set!: "bytevector-s40-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-s40-set!: "bytevector-s40-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector-s40-set!: "bytevector-s40-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-s40-set!: "bytevector-s40-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-s40-set!: "bytevector-s40-set!: invalid index 19 for 5-byte field of bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-s40-set!: "bytevector-s40-set!: invalid index 22 for 5-byte field of bytevector #vu8(173 173 173 173 173 173 ...)".
@@ -2514,8 +2521,8 @@ bytevector.mo:Expected error in mat bytevector-u40-set!: "incorrect argument cou
 bytevector.mo:Expected error in mat bytevector-u40-set!: "incorrect argument count in call (bytevector-u40-set! $v1 0)".
 bytevector.mo:Expected error in mat bytevector-u40-set!: "incorrect argument count in call (bytevector-u40-set! $v1 0 0)".
 bytevector.mo:Expected error in mat bytevector-u40-set!: "incorrect argument count in call (bytevector-u40-set! $v1 0 0 (quote big) 0)".
-bytevector.mo:Expected error in mat bytevector-u40-set!: "bytevector-u40-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-u40-set!: "bytevector-u40-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-u40-set!: "bytevector-u40-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector-u40-set!: "bytevector-u40-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-u40-set!: "bytevector-u40-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-u40-set!: "bytevector-u40-set!: invalid index 19 for 5-byte field of bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-u40-set!: "bytevector-u40-set!: invalid index 22 for 5-byte field of bytevector #vu8(173 173 173 173 173 173 ...)".
@@ -2558,8 +2565,8 @@ bytevector.mo:Expected error in mat bytevector-s48-set!: "incorrect argument cou
 bytevector.mo:Expected error in mat bytevector-s48-set!: "incorrect argument count in call (bytevector-s48-set! $v1 0)".
 bytevector.mo:Expected error in mat bytevector-s48-set!: "incorrect argument count in call (bytevector-s48-set! $v1 0 0)".
 bytevector.mo:Expected error in mat bytevector-s48-set!: "incorrect argument count in call (bytevector-s48-set! $v1 0 0 (quote big) 0)".
-bytevector.mo:Expected error in mat bytevector-s48-set!: "bytevector-s48-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-s48-set!: "bytevector-s48-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-s48-set!: "bytevector-s48-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector-s48-set!: "bytevector-s48-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-s48-set!: "bytevector-s48-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-s48-set!: "bytevector-s48-set!: invalid index 18 for 6-byte field of bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-s48-set!: "bytevector-s48-set!: invalid index 22 for 6-byte field of bytevector #vu8(173 173 173 173 173 173 ...)".
@@ -2576,8 +2583,8 @@ bytevector.mo:Expected error in mat bytevector-u48-set!: "incorrect argument cou
 bytevector.mo:Expected error in mat bytevector-u48-set!: "incorrect argument count in call (bytevector-u48-set! $v1 0)".
 bytevector.mo:Expected error in mat bytevector-u48-set!: "incorrect argument count in call (bytevector-u48-set! $v1 0 0)".
 bytevector.mo:Expected error in mat bytevector-u48-set!: "incorrect argument count in call (bytevector-u48-set! $v1 0 0 (quote big) 0)".
-bytevector.mo:Expected error in mat bytevector-u48-set!: "bytevector-u48-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-u48-set!: "bytevector-u48-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-u48-set!: "bytevector-u48-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector-u48-set!: "bytevector-u48-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-u48-set!: "bytevector-u48-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-u48-set!: "bytevector-u48-set!: invalid index 18 for 6-byte field of bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-u48-set!: "bytevector-u48-set!: invalid index 22 for 6-byte field of bytevector #vu8(173 173 173 173 173 173 ...)".
@@ -2620,8 +2627,8 @@ bytevector.mo:Expected error in mat bytevector-s56-set!: "incorrect argument cou
 bytevector.mo:Expected error in mat bytevector-s56-set!: "incorrect argument count in call (bytevector-s56-set! $v1 0)".
 bytevector.mo:Expected error in mat bytevector-s56-set!: "incorrect argument count in call (bytevector-s56-set! $v1 0 0)".
 bytevector.mo:Expected error in mat bytevector-s56-set!: "incorrect argument count in call (bytevector-s56-set! $v1 0 0 (quote big) 0)".
-bytevector.mo:Expected error in mat bytevector-s56-set!: "bytevector-s56-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-s56-set!: "bytevector-s56-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-s56-set!: "bytevector-s56-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector-s56-set!: "bytevector-s56-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-s56-set!: "bytevector-s56-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-s56-set!: "bytevector-s56-set!: invalid index 17 for 7-byte field of bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-s56-set!: "bytevector-s56-set!: invalid index 22 for 7-byte field of bytevector #vu8(173 173 173 173 173 173 ...)".
@@ -2638,8 +2645,8 @@ bytevector.mo:Expected error in mat bytevector-u56-set!: "incorrect argument cou
 bytevector.mo:Expected error in mat bytevector-u56-set!: "incorrect argument count in call (bytevector-u56-set! $v1 0)".
 bytevector.mo:Expected error in mat bytevector-u56-set!: "incorrect argument count in call (bytevector-u56-set! $v1 0 0)".
 bytevector.mo:Expected error in mat bytevector-u56-set!: "incorrect argument count in call (bytevector-u56-set! $v1 0 0 (quote big) 0)".
-bytevector.mo:Expected error in mat bytevector-u56-set!: "bytevector-u56-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-u56-set!: "bytevector-u56-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-u56-set!: "bytevector-u56-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector-u56-set!: "bytevector-u56-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-u56-set!: "bytevector-u56-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-u56-set!: "bytevector-u56-set!: invalid index 17 for 7-byte field of bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-u56-set!: "bytevector-u56-set!: invalid index 22 for 7-byte field of bytevector #vu8(173 173 173 173 173 173 ...)".
@@ -2719,8 +2726,8 @@ bytevector.mo:Expected error in mat bytevector-s64-native-set!: "incorrect argum
 bytevector.mo:Expected error in mat bytevector-s64-native-set!: "incorrect argument count in call (bytevector-s64-native-set! $v1)".
 bytevector.mo:Expected error in mat bytevector-s64-native-set!: "incorrect argument count in call (bytevector-s64-native-set! $v1 0)".
 bytevector.mo:Expected error in mat bytevector-s64-native-set!: "incorrect argument count in call (bytevector-s64-native-set! $v1 0 0 15)".
-bytevector.mo:Expected error in mat bytevector-s64-native-set!: "bytevector-s64-native-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-s64-native-set!: "bytevector-s64-native-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-s64-native-set!: "bytevector-s64-native-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector-s64-native-set!: "bytevector-s64-native-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-s64-native-set!: "bytevector-s64-native-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-s64-native-set!: "bytevector-s64-native-set!: invalid index 1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-s64-native-set!: "bytevector-s64-native-set!: invalid index 2 for bytevector #vu8(173 173 173 173 173 173 ...)".
@@ -2756,8 +2763,8 @@ bytevector.mo:Expected error in mat bytevector-u64-native-set!: "incorrect argum
 bytevector.mo:Expected error in mat bytevector-u64-native-set!: "incorrect argument count in call (bytevector-u64-native-set! $v1)".
 bytevector.mo:Expected error in mat bytevector-u64-native-set!: "incorrect argument count in call (bytevector-u64-native-set! $v1 0)".
 bytevector.mo:Expected error in mat bytevector-u64-native-set!: "incorrect argument count in call (bytevector-u64-native-set! $v1 0 0 15)".
-bytevector.mo:Expected error in mat bytevector-u64-native-set!: "bytevector-u64-native-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-u64-native-set!: "bytevector-u64-native-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-u64-native-set!: "bytevector-u64-native-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector-u64-native-set!: "bytevector-u64-native-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-u64-native-set!: "bytevector-u64-native-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-u64-native-set!: "bytevector-u64-native-set!: invalid index 1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-u64-native-set!: "bytevector-u64-native-set!: invalid index 2 for bytevector #vu8(173 173 173 173 173 173 ...)".
@@ -2832,8 +2839,8 @@ bytevector.mo:Expected error in mat bytevector-s64-set!: "incorrect argument cou
 bytevector.mo:Expected error in mat bytevector-s64-set!: "incorrect argument count in call (bytevector-s64-set! $v1 0)".
 bytevector.mo:Expected error in mat bytevector-s64-set!: "incorrect argument count in call (bytevector-s64-set! $v1 0 0)".
 bytevector.mo:Expected error in mat bytevector-s64-set!: "incorrect argument count in call (bytevector-s64-set! $v1 0 0 (quote big) 15)".
-bytevector.mo:Expected error in mat bytevector-s64-set!: "bytevector-s64-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-s64-set!: "bytevector-s64-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-s64-set!: "bytevector-s64-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector-s64-set!: "bytevector-s64-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-s64-set!: "bytevector-s64-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-s64-set!: "bytevector-s64-set!: invalid index <int> for 8-byte field of bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-s64-set!: "bytevector-s64-set!: invalid index <int> for 8-byte field of bytevector #vu8(173 173 173 173 173 173 ...)".
@@ -2855,8 +2862,8 @@ bytevector.mo:Expected error in mat bytevector-u64-set!: "incorrect argument cou
 bytevector.mo:Expected error in mat bytevector-u64-set!: "incorrect argument count in call (bytevector-u64-set! $v1 0)".
 bytevector.mo:Expected error in mat bytevector-u64-set!: "incorrect argument count in call (bytevector-u64-set! $v1 0 0)".
 bytevector.mo:Expected error in mat bytevector-u64-set!: "incorrect argument count in call (bytevector-u64-set! $v1 0 0 (quote big) 15)".
-bytevector.mo:Expected error in mat bytevector-u64-set!: "bytevector-u64-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-u64-set!: "bytevector-u64-set!: #(0 0 0 0 0 0 ...) is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-u64-set!: "bytevector-u64-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector-u64-set!: "bytevector-u64-set!: #(0 0 0 0 0 0 ...) is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-u64-set!: "bytevector-u64-set!: invalid index -1 for bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-u64-set!: "bytevector-u64-set!: invalid index <int> for 8-byte field of bytevector #vu8(173 173 173 173 173 173 ...)".
 bytevector.mo:Expected error in mat bytevector-u64-set!: "bytevector-u64-set!: invalid index <int> for 8-byte field of bytevector #vu8(173 173 173 173 173 173 ...)".
@@ -2957,8 +2964,8 @@ bytevector.mo:Expected error in mat bytevector-ieee-single-native-set!: "incorre
 bytevector.mo:Expected error in mat bytevector-ieee-single-native-set!: "incorrect argument count in call (bytevector-ieee-single-native-set! $v1)".
 bytevector.mo:Expected error in mat bytevector-ieee-single-native-set!: "incorrect argument count in call (bytevector-ieee-single-native-set! $v1 0)".
 bytevector.mo:Expected error in mat bytevector-ieee-single-native-set!: "incorrect argument count in call (bytevector-ieee-single-native-set! $v1 0 0.0 0.0)".
-bytevector.mo:Expected error in mat bytevector-ieee-single-native-set!: "bytevector-ieee-single-native-set!: #(3 252 5 0 0 0 ...) is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-ieee-single-native-set!: "bytevector-ieee-single-native-set!: #(3 252 5 0 0 0 ...) is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-ieee-single-native-set!: "bytevector-ieee-single-native-set!: #(3 252 5 0 0 0 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector-ieee-single-native-set!: "bytevector-ieee-single-native-set!: #(3 252 5 0 0 0 ...) is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-ieee-single-native-set!: "bytevector-ieee-single-native-set!: invalid index -1 for bytevector #vu8(235 235 235 235 235 235 ...)".
 bytevector.mo:Expected error in mat bytevector-ieee-single-native-set!: "bytevector-ieee-single-native-set!: invalid index 1 for bytevector #vu8(235 235 235 235 235 235 ...)".
 bytevector.mo:Expected error in mat bytevector-ieee-single-native-set!: "bytevector-ieee-single-native-set!: invalid index 2 for bytevector #vu8(235 235 235 235 235 235 ...)".
@@ -2994,8 +3001,8 @@ bytevector.mo:Expected error in mat bytevector-ieee-double-native-set!: "incorre
 bytevector.mo:Expected error in mat bytevector-ieee-double-native-set!: "incorrect argument count in call (bytevector-ieee-double-native-set! $v1)".
 bytevector.mo:Expected error in mat bytevector-ieee-double-native-set!: "incorrect argument count in call (bytevector-ieee-double-native-set! $v1 0)".
 bytevector.mo:Expected error in mat bytevector-ieee-double-native-set!: "incorrect argument count in call (bytevector-ieee-double-native-set! $v1 0 0.0 0.0)".
-bytevector.mo:Expected error in mat bytevector-ieee-double-native-set!: "bytevector-ieee-double-native-set!: #(3 252 5 0 0 0 ...) is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-ieee-double-native-set!: "bytevector-ieee-double-native-set!: #(3 252 5 0 0 0 ...) is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-ieee-double-native-set!: "bytevector-ieee-double-native-set!: #(3 252 5 0 0 0 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector-ieee-double-native-set!: "bytevector-ieee-double-native-set!: #(3 252 5 0 0 0 ...) is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-ieee-double-native-set!: "bytevector-ieee-double-native-set!: invalid index -1 for bytevector #vu8(235 235 235 235 235 235 ...)".
 bytevector.mo:Expected error in mat bytevector-ieee-double-native-set!: "bytevector-ieee-double-native-set!: invalid index 1 for bytevector #vu8(235 235 235 235 235 235 ...)".
 bytevector.mo:Expected error in mat bytevector-ieee-double-native-set!: "bytevector-ieee-double-native-set!: invalid index 2 for bytevector #vu8(235 235 235 235 235 235 ...)".
@@ -3078,8 +3085,8 @@ bytevector.mo:Expected error in mat bytevector-ieee-single-set!: "incorrect argu
 bytevector.mo:Expected error in mat bytevector-ieee-single-set!: "incorrect argument count in call (bytevector-ieee-single-set! $v1 0)".
 bytevector.mo:Expected error in mat bytevector-ieee-single-set!: "incorrect argument count in call (bytevector-ieee-single-set! $v1 0 0.0)".
 bytevector.mo:Expected error in mat bytevector-ieee-single-set!: "incorrect argument count in call (bytevector-ieee-single-set! $v1 0 0.0 (quote big) (quote bigger))".
-bytevector.mo:Expected error in mat bytevector-ieee-single-set!: "bytevector-ieee-single-set!: #(3 252 5 0 0 0 ...) is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-ieee-single-set!: "bytevector-ieee-single-set!: #(3 252 5 0 0 0 ...) is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-ieee-single-set!: "bytevector-ieee-single-set!: #(3 252 5 0 0 0 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector-ieee-single-set!: "bytevector-ieee-single-set!: #(3 252 5 0 0 0 ...) is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-ieee-single-set!: "bytevector-ieee-single-set!: invalid index -1 for bytevector #vu8(235 235 235 235 235 235 ...)".
 bytevector.mo:Expected error in mat bytevector-ieee-single-set!: "bytevector-ieee-single-set!: invalid index 36 for 4-byte field of bytevector #vu8(235 235 235 235 235 235 ...)".
 bytevector.mo:Expected error in mat bytevector-ieee-single-set!: "bytevector-ieee-single-set!: invalid index 37 for 4-byte field of bytevector #vu8(235 235 235 235 235 235 ...)".
@@ -3099,8 +3106,8 @@ bytevector.mo:Expected error in mat bytevector-ieee-double-set!: "incorrect argu
 bytevector.mo:Expected error in mat bytevector-ieee-double-set!: "incorrect argument count in call (bytevector-ieee-double-set! $v1 0)".
 bytevector.mo:Expected error in mat bytevector-ieee-double-set!: "incorrect argument count in call (bytevector-ieee-double-set! $v1 0 0.0)".
 bytevector.mo:Expected error in mat bytevector-ieee-double-set!: "incorrect argument count in call (bytevector-ieee-double-set! $v1 0 0.0 (quote big) (quote bigger))".
-bytevector.mo:Expected error in mat bytevector-ieee-double-set!: "bytevector-ieee-double-set!: #(3 252 5 0 0 0 ...) is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-ieee-double-set!: "bytevector-ieee-double-set!: #(3 252 5 0 0 0 ...) is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-ieee-double-set!: "bytevector-ieee-double-set!: #(3 252 5 0 0 0 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector-ieee-double-set!: "bytevector-ieee-double-set!: #(3 252 5 0 0 0 ...) is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-ieee-double-set!: "bytevector-ieee-double-set!: invalid index -1 for bytevector #vu8(235 235 235 235 235 235 ...)".
 bytevector.mo:Expected error in mat bytevector-ieee-double-set!: "bytevector-ieee-double-set!: invalid index <int> for 8-byte field of bytevector #vu8(235 235 235 235 235 235 ...)".
 bytevector.mo:Expected error in mat bytevector-ieee-double-set!: "bytevector-ieee-double-set!: invalid index <int> for 8-byte field of bytevector #vu8(235 235 235 235 235 235 ...)".
@@ -3206,8 +3213,8 @@ bytevector.mo:Expected error in mat bytevector-sint-set!: "incorrect argument co
 bytevector.mo:Expected error in mat bytevector-sint-set!: "incorrect argument count in call (bytevector-sint-set! $v1 0 7)".
 bytevector.mo:Expected error in mat bytevector-sint-set!: "incorrect argument count in call (bytevector-sint-set! $v1 0 7 (quote big))".
 bytevector.mo:Expected error in mat bytevector-sint-set!: "incorrect argument count in call (bytevector-sint-set! $v1 0 7 (quote big) 5 ...)".
-bytevector.mo:Expected error in mat bytevector-sint-set!: "bytevector-sint-set!: #(3 252 5 0 0 0 ...) is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-sint-set!: "bytevector-sint-set!: #(3 252 5 0 0 0 ...) is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-sint-set!: "bytevector-sint-set!: #(3 252 5 0 0 0 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector-sint-set!: "bytevector-sint-set!: #(3 252 5 0 0 0 ...) is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-sint-set!: "bytevector-sint-set!: invalid index -1 for bytevector #vu8(0 0 0 0 0 0 ...)".
 bytevector.mo:Expected error in mat bytevector-sint-set!: "bytevector-sint-set!: invalid index -1 for bytevector #vu8(0 0 0 0 0 0 ...)".
 bytevector.mo:Expected error in mat bytevector-sint-set!: "bytevector-sint-set!: invalid index -1 for bytevector #vu8(0 0 0 0 0 0 ...)".
@@ -3270,8 +3277,8 @@ bytevector.mo:Expected error in mat bytevector-uint-set!: "incorrect argument co
 bytevector.mo:Expected error in mat bytevector-uint-set!: "incorrect argument count in call (bytevector-uint-set! $v1 0 7)".
 bytevector.mo:Expected error in mat bytevector-uint-set!: "incorrect argument count in call (bytevector-uint-set! $v1 0 7 (quote big))".
 bytevector.mo:Expected error in mat bytevector-uint-set!: "incorrect argument count in call (bytevector-uint-set! $v1 0 7 (quote big) 5 ...)".
-bytevector.mo:Expected error in mat bytevector-uint-set!: "bytevector-uint-set!: #(3 252 5 0 0 0 ...) is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-uint-set!: "bytevector-uint-set!: #(3 252 5 0 0 0 ...) is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-uint-set!: "bytevector-uint-set!: #(3 252 5 0 0 0 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector-uint-set!: "bytevector-uint-set!: #(3 252 5 0 0 0 ...) is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-uint-set!: "bytevector-uint-set!: invalid index -1 for bytevector #vu8(0 0 0 0 0 0 ...)".
 bytevector.mo:Expected error in mat bytevector-uint-set!: "bytevector-uint-set!: invalid index -1 for bytevector #vu8(0 0 0 0 0 0 ...)".
 bytevector.mo:Expected error in mat bytevector-uint-set!: "bytevector-uint-set!: invalid index -1 for bytevector #vu8(0 0 0 0 0 0 ...)".
@@ -3339,7 +3346,7 @@ bytevector.mo:Expected error in mat bytevector-copy!: "incorrect argument count
 bytevector.mo:Expected error in mat bytevector-copy!: "incorrect argument count in call (bytevector-copy! $v2 3 $v1 1)".
 bytevector.mo:Expected error in mat bytevector-copy!: "incorrect argument count in call (bytevector-copy! $v2 3 $v1 1 2 ...)".
 bytevector.mo:Expected error in mat bytevector-copy!: "bytevector-copy!: 0 is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-copy!: "bytevector-copy!: #(1 2 3) is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-copy!: "bytevector-copy!: #(1 2 3) is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-copy!: "bytevector-copy!: invalid start value -1".
 bytevector.mo:Expected error in mat bytevector-copy!: "bytevector-copy!: invalid start value -1".
 bytevector.mo:Expected error in mat bytevector-copy!: "bytevector-copy!: invalid start value a".
@@ -3364,8 +3371,8 @@ bytevector.mo:Expected error in mat bytevector-copy!: "bytevector-copy!: index 5
 bytevector.mo:Expected error in mat bytevector-truncate!: "incorrect argument count in call (bytevector-truncate!)".
 bytevector.mo:Expected error in mat bytevector-truncate!: "incorrect argument count in call (bytevector-truncate! $v)".
 bytevector.mo:Expected error in mat bytevector-truncate!: "incorrect argument count in call (bytevector-truncate! $v 3 15)".
-bytevector.mo:Expected error in mat bytevector-truncate!: "bytevector-truncate!: 0 is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-truncate!: "bytevector-truncate!: "abc" is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-truncate!: "bytevector-truncate!: 0 is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector-truncate!: "bytevector-truncate!: "abc" is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-truncate!: "bytevector-truncate!: invalid new length -1 for #vu8(1 2 3 4 5 6 ...)".
 bytevector.mo:Expected error in mat bytevector-truncate!: "bytevector-truncate!: invalid new length 10 for #vu8(1 2 3 4 5 6 ...)".
 bytevector.mo:Expected error in mat bytevector-truncate!: "bytevector-truncate!: invalid new length 1000 for #vu8(1 2 3 4 5 6 ...)".
@@ -3374,8 +3381,8 @@ bytevector.mo:Expected error in mat bytevector-truncate!: "bytevector-truncate!:
 bytevector.mo:Expected error in mat bytevector-fill!: "incorrect argument count in call (bytevector-fill!)".
 bytevector.mo:Expected error in mat bytevector-fill!: "incorrect argument count in call (bytevector-fill! $v1)".
 bytevector.mo:Expected error in mat bytevector-fill!: "incorrect argument count in call (bytevector-fill! $v1 0 0)".
-bytevector.mo:Expected error in mat bytevector-fill!: "bytevector-fill!: a is not a bytevector".
-bytevector.mo:Expected error in mat bytevector-fill!: "bytevector-fill!: #(1) is not a bytevector".
+bytevector.mo:Expected error in mat bytevector-fill!: "bytevector-fill!: a is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector-fill!: "bytevector-fill!: #(1) is not a mutable bytevector".
 bytevector.mo:Expected error in mat bytevector-fill!: "bytevector-fill!: -129 is not a valid fill value".
 bytevector.mo:Expected error in mat bytevector-fill!: "bytevector-fill!: 256 is not a valid fill value".
 bytevector.mo:Expected error in mat bytevector-fill!: "bytevector-fill!: a is not a valid fill value".
@@ -3535,6 +3542,37 @@ bytevector.mo:Expected error in mat bytevector=?: "incorrect argument count in c
 bytevector.mo:Expected error in mat bytevector=?: "bytevector=?: a is not a bytevector".
 bytevector.mo:Expected error in mat bytevector=?: "bytevector=?: "a" is not a bytevector".
 bytevector.mo:Expected error in mat tspl/csug-examples: "invalid endianness "spam"".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-uint-set!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-sint-set!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-u8-set!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-s8-set!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-u16-set!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-s16-set!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-u16-native-set!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-s16-native-set!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-u24-set!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-s24-set!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-u32-set!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-s32-set!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-u32-native-set!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-s32-native-set!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-u40-set!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-s40-set!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-u48-set!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-s48-set!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-u56-set!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-s56-set!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-u64-set!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-s64-set!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-u64-native-set!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-s64-native-set!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-ieee-single-set!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-ieee-double-set!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-ieee-single-native-set!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-ieee-double-native-set!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-fill!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-copy!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-truncate!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
 misc.mo:Expected error in mat compiler1: "variable i-am-not-bound is not bound".
 misc.mo:Expected error in mat compiler1: "attempt to apply non-procedure oops".
 misc.mo:Expected error in mat compiler1: "incorrect argument count in call (g (list))".
@@ -3749,7 +3787,7 @@ cp0.mo:Expected error in mat expand-output: "expand-output: #t is not a textual
 cp0.mo:Expected error in mat expand-output: "expand-output: #<binary output port bytevector> is not a textual output port or #f".
 cp0.mo:Expected error in mat expand/optimize-output: "expand/optimize-output: #t is not a textual output port or #f".
 cp0.mo:Expected error in mat expand/optimize-output: "expand/optimize-output: #<binary output port bytevector> is not a textual output port or #f".
-5_6.mo:Expected error in mat make-vector: "make-vector: a is not a nonnegative fixnum".
+5_6.mo:Expected error in mat make-vector: "make-vector: a is not a valid vector length".
 5_6.mo:Expected error in mat vector-length: "vector-length: (a b c) is not a vector".
 5_6.mo:Expected error in mat vector-ref: "vector-ref: 3 is not a valid index for #(a b c)".
 5_6.mo:Expected error in mat vector-ref: "vector-ref: -1 is not a valid index for #(a b c)".
@@ -3758,16 +3796,16 @@ cp0.mo:Expected error in mat expand/optimize-output: "expand/optimize-output: #<
 5_6.mo:Expected error in mat vector-set!: "vector-set!: 3 is not a valid index for #(a b c)".
 5_6.mo:Expected error in mat vector-set!: "vector-set!: -1 is not a valid index for #(a b c)".
 5_6.mo:Expected error in mat vector-set!: "vector-set!: a is not a valid index for #(a b c)".
-5_6.mo:Expected error in mat vector-set!: "vector-set!: (a b c) is not a vector".
+5_6.mo:Expected error in mat vector-set!: "vector-set!: (a b c) is not a mutable vector".
 5_6.mo:Expected error in mat vector-set-fixnum!: "vector-set-fixnum!: 3 is not a valid index for #(a b c)".
 5_6.mo:Expected error in mat vector-set-fixnum!: "vector-set-fixnum!: -1 is not a valid index for #(a b c)".
 5_6.mo:Expected error in mat vector-set-fixnum!: "vector-set-fixnum!: a is not a valid index for #(a b c)".
-5_6.mo:Expected error in mat vector-set-fixnum!: "vector-set-fixnum!: (a b c) is not a vector".
+5_6.mo:Expected error in mat vector-set-fixnum!: "vector-set-fixnum!: (a b c) is not a mutable vector".
 5_6.mo:Expected error in mat vector-set-fixnum!: "vector-set-fixnum!: d is not a fixnum".
 5_6.mo:Expected error in mat vector-set-fixnum!: "vector-set-fixnum!: #\d is not a fixnum".
 5_6.mo:Expected error in mat vector-set-fixnum!: "vector-set-fixnum!: (a b c) is not a fixnum".
 5_6.mo:Expected error in mat vector-copy: "vector-copy: (a b c) is not a vector".
-5_6.mo:Expected error in mat vector-fill!: "vector-fill!: #vfx() is not a vector".
+5_6.mo:Expected error in mat vector-fill!: "vector-fill!: #vfx() is not a mutable vector".
 5_6.mo:Expected error in mat list->vector: "list->vector: #(a b c) is not a proper list".
 5_6.mo:Expected error in mat list->vector: "list->vector: (#\a #\b . #\c) is not a proper list".
 5_6.mo:Expected error in mat list->vector: "list->vector: (#\a #\b #\c #\b #\c #\b ...) is circular".
@@ -3788,11 +3826,11 @@ cp0.mo:Expected error in mat expand/optimize-output: "expand/optimize-output: #<
 5_6.mo:Expected error in mat fxvector-set!: "fxvector-set!: -1 is not a valid index for #vfx(3 4 5)".
 5_6.mo:Expected error in mat fxvector-set!: "fxvector-set!: a is not a valid index for #vfx(3 4 5)".
 5_6.mo:Expected error in mat fxvector-set!: "fxvector-set!: d is not a fixnum".
-5_6.mo:Expected error in mat fxvector-set!: "fxvector-set!: (3 4 5) is not an fxvector".
+5_6.mo:Expected error in mat fxvector-set!: "fxvector-set!: (3 4 5) is not a mutable fxvector".
 5_6.mo:Expected error in mat fxvector-set!: "fxvector-set!: <-int> is not a fixnum".
 5_6.mo:Expected error in mat fxvector-set!: "fxvector-set!: <int> is not a fixnum".
-5_6.mo:Expected error in mat fxvector-set!: "fxvector-set!: (3 4 5) is not an fxvector".
-5_6.mo:Expected error in mat fxvector-set!: "fxvector-set!: #(3 4) is not an fxvector".
+5_6.mo:Expected error in mat fxvector-set!: "fxvector-set!: (3 4 5) is not a mutable fxvector".
+5_6.mo:Expected error in mat fxvector-set!: "fxvector-set!: #(3 4) is not a mutable fxvector".
 5_6.mo:Expected error in mat fxvector-set!: "fxvector-set!: 3 is not a valid index for #vfx(3 4 5)".
 5_6.mo:Expected error in mat fxvector-set!: "fxvector-set!: -3 is not a valid index for #vfx(3 4 5)".
 5_6.mo:Expected error in mat fxvector-set!: "fxvector-set!: <int> is not a valid index for #vfx(3 4 5)".
@@ -3803,7 +3841,7 @@ cp0.mo:Expected error in mat expand/optimize-output: "expand/optimize-output: #<
 5_6.mo:Expected error in mat fxvector-set!: "fxvector-set!: a is not a fixnum".
 5_6.mo:Expected error in mat fxvector-copy: "fxvector-copy: (a b c) is not an fxvector".
 5_6.mo:Expected error in mat fxvector-fill!: "fxvector-fill!: a is not a fixnum".
-5_6.mo:Expected error in mat fxvector-fill!: "fxvector-fill!: #(1) is not an fxvector".
+5_6.mo:Expected error in mat fxvector-fill!: "fxvector-fill!: #(1) is not a mutable fxvector".
 5_6.mo:Expected error in mat list->fxvector: "list->fxvector: #(a b c) is not a proper list".
 5_6.mo:Expected error in mat list->fxvector: "list->fxvector: (1 2 . 3) is not a proper list".
 5_6.mo:Expected error in mat list->fxvector: "list->fxvector: (1 2 3 2 3 2 ...) is circular".
@@ -3854,10 +3892,16 @@ cp0.mo:Expected error in mat expand/optimize-output: "expand/optimize-output: #<
 5_6.mo:Expected error in mat vector-sort!: "incorrect argument count in call (vector-sort! >)".
 5_6.mo:Expected error in mat vector-sort!: "incorrect argument count in call (vector-sort! (quote #(a b c)))".
 5_6.mo:Expected error in mat vector-sort!: "incorrect argument count in call (vector-sort! > (quote #(1 2 3)) #t)".
-5_6.mo:Expected error in mat vector-sort!: "vector-sort!: 3 is not a vector".
-5_6.mo:Expected error in mat vector-sort!: "vector-sort!: (1 2 3) is not a vector".
+5_6.mo:Expected error in mat vector-sort!: "vector-sort!: 3 is not a mutable vector".
+5_6.mo:Expected error in mat vector-sort!: "vector-sort!: (1 2 3) is not a mutable vector".
 5_6.mo:Expected error in mat vector-sort!: "vector-sort!: #(a b c) is not a procedure".
 5_6.mo:Expected error in mat vector-sort!: ">: b is not a real number".
+5_6.mo:Expected error in mat vector->immutable-vector: "vector-set!: #(1 2 3) is not a mutable vector".
+5_6.mo:Expected error in mat vector->immutable-vector: "vector-set-fixnum!: #(1 2 3) is not a mutable vector".
+5_6.mo:Expected error in mat vector->immutable-vector: "vector-fill!: #(1 2 3) is not a mutable vector".
+5_6.mo:Expected error in mat vector->immutable-vector: "vector-sort!: #(1 2 3) is not a mutable vector".
+5_6.mo:Expected error in mat fxvector->immutable-fxvector: "fxvector-set!: #vfx(1 2 3) is not a mutable fxvector".
+5_6.mo:Expected error in mat fxvector->immutable-fxvector: "fxvector-fill!: #vfx(1 2 3) is not a mutable fxvector".
 5_7.mo:Expected error in mat string->symbol: "string->symbol: 3 is not a string".
 5_7.mo:Expected error in mat string->symbol: "string->symbol: a is not a string".
 5_7.mo:Expected error in mat gensym: "gensym: #(a b c) is not a string".
diff --git a/s/5_4.ss b/s/5_4.ss
index 3948195194..892fcc5c5f 100644
--- a/s/5_4.ss
+++ b/s/5_4.ss
@@ -94,7 +94,7 @@
 (define-who string-copy!
   (lambda (s1 i1 s2 i2 k)
     (unless (string? s1) ($oops who "~s is not a string" s1))
-    (unless (string? s2) ($oops who "~s is not a string" s2))
+    (unless (mutable-string? s2) ($oops who "~s is not a mutable string" s2))
     (let ([n1 (string-length s1)] [n2 (string-length s2)])
       (unless (and (fixnum? i1) (fx>= i1 0))
         ($oops who "invalid start value ~s" i1))
@@ -109,10 +109,22 @@
     ; whew!
       (#3%string-copy! s1 i1 s2 i2 k))))
 
+(set-who! string->immutable-string
+  (lambda (v)
+    (unless (string? v)
+      ($oops who "~s is not a string" v))
+    (cond
+      [(immutable-string? v) v]
+      [(fx= 0 (string-length v)) ($tc-field 'null-immutable-string ($tc))]
+      [else
+       (let ([v2 (string-copy v)])
+         ($string-set-immutable! v2)
+         v2)])))
+
 (define substring-fill!
    (lambda (s m n c)
-      (unless (string? s)
-         ($oops 'substring-fill! "~s is not a string" s))
+      (unless (mutable-string? s)
+         ($oops 'substring-fill! "~s is not a mutable string" s))
       (unless (char? c)
          ($oops 'substring-fill! "~s is not a character" c))
       (let ([k (string-length s)])
diff --git a/s/5_6.ss b/s/5_6.ss
index 70f5887165..fa5be7339a 100644
--- a/s/5_6.ss
+++ b/s/5_6.ss
@@ -69,9 +69,21 @@
       ($oops 'vector-copy "~s is not a vector" v))
     ($vector-copy v (vector-length v))))
 
+(set-who! vector->immutable-vector
+  (lambda (v)
+    (unless (vector? v)
+      ($oops who "~s is not a vector" v))
+    (cond
+      [(immutable-vector? v) v]
+      [(fx= 0 (vector-length v)) ($tc-field 'null-immutable-vector ($tc))]
+      [else
+       (let ([v2 (vector-copy v)])
+         ($vector-set-immutable! v2)
+         v2)])))
+
 (set-who! vector-fill!
   (lambda (v obj)
-    (unless (vector? v) ($oops who "~s is not a vector" v))
+    (unless (mutable-vector? v) ($oops who "~s is not a mutable vector" v))
     (let ([n (vector-length v)])
       (do ([i 0 (fx+ i 1)])
           ((fx= i n) v)
@@ -116,6 +128,18 @@
               (constant fxvector-data-disp) n))
         fxv2))))
 
+(set-who! fxvector->immutable-fxvector
+  (lambda (v)
+    (unless (fxvector? v)
+      ($oops who "~s is not a fxvector" v))
+    (cond
+      [(immutable-fxvector? v) v]
+      [(fx= 0 (fxvector-length v)) ($tc-field 'null-immutable-fxvector ($tc))]
+      [else
+       (let ([v2 (fxvector-copy v)])
+         ($fxvector-set-immutable! v2)
+         v2)])))
+
 (set! vector-map
   (case-lambda
     [(p v)
@@ -347,7 +371,7 @@
   (set-who! vector-sort!
     (lambda (elt< v)
       (unless (procedure? elt<) ($oops who "~s is not a procedure" elt<))
-      (unless (vector? v) ($oops who "~s is not a vector" v))
+      (unless (mutable-vector? v) ($oops who "~s is not a mutable vector" v))
       (let ([n (vector-length v)])
         (unless (fx<= n 1)
           (let ([outvec (dovsort! elt< v n)])
diff --git a/s/bytevector.ss b/s/bytevector.ss
index b02f02f681..e7f547b821 100644
--- a/s/bytevector.ss
+++ b/s/bytevector.ss
@@ -62,6 +62,9 @@
   (define (not-a-bytevector who v)
     ($oops who "~s is not a bytevector" v))
 
+  (define (not-a-mutable-bytevector who v)
+    ($oops who "~s is not a mutable bytevector" v))
+
   (define (invalid-index who v i)
     ($oops who "invalid index ~s for bytevector ~s" i v))
 
@@ -452,7 +455,7 @@
                                          #'unsigned-value-pred)])
              #`(let ([value-okay? (value-pred bits)])
                  (lambda (v i k eness who)
-                   (unless (bytevector? v) (not-a-bytevector who v))
+                   (unless (mutable-bytevector? v) (not-a-mutable-bytevector who v))
                    (unaligned-ref-check who (fxquotient bits 8) v i)
                    (unless (value-okay? k) (invalid-value who k))
                    (case eness
@@ -499,15 +502,16 @@
   (set-who! make-bytevector
     (case-lambda
       [(n fill)
-      ; if this fails, we have to change the test and message below
-       (meta-assert (= (constant maximum-bytevector-length) (constant most-positive-fixnum)))
-       (unless (and (fixnum? n) (fx>= n 0)) ($oops who "~s is not a nonnegative fixnum" n))
+       (meta-assert (<= (constant maximum-bytevector-length) (constant most-positive-fixnum)))
+       (unless (and (fixnum? n) ($fxu< n (fx+ (constant maximum-bytevector-length) 1)))
+         ($oops who "~s is not a valid bytevector length" n))
        (unless (fill? fill) (invalid-fill-value who fill))
        (#3%make-bytevector n fill)]
       [(n)
-      ; if this fails, we have to change the test and message below
-       (meta-assert (= (constant maximum-bytevector-length) (constant most-positive-fixnum)))
-       (unless (and (fixnum? n) (fx>= n 0)) ($oops who "~s is not a nonnegative fixnum" n))
+       (meta-assert (<= (constant maximum-bytevector-length) (constant most-positive-fixnum)))
+       (unless (and (fixnum? n) ($fxu< n (fx+ (constant maximum-bytevector-length) 1)))
+         ($oops who "~s is not a valid bytevector length" n))
+       (unless (fx<= n (constant maximum-bytevector-length)) ($oops who "~s is too large" n))
        (#3%make-bytevector n)]))
 
   (set! bytevector? (lambda (x) (#2%bytevector? x)))
@@ -516,6 +520,20 @@
     (lambda (v)
       (#2%bytevector-length v)))
 
+  (set-who! $bytevector-set-immutable!
+    (lambda (v)
+      (unless (bytevector? v)
+        ($oops who "~s is not a bytevector" v))
+      (#3%$bytevector-set-immutable! v)))
+
+  (set-who! mutable-bytevector?
+    (lambda (v)
+      (#3%mutable-bytevector? v)))
+
+  (set-who! immutable-bytevector?
+    (lambda (v)
+      (#3%immutable-bytevector? v)))
+
   (set! bytevector-s8-ref
     (lambda (v i)
       (#2%bytevector-s8-ref v i)))
@@ -534,13 +552,13 @@
 
   (set-who! $bytevector-set!
     (lambda (v i fill)
-      (if ($bytevector-ref-check? 8 v i)
+      (if ($bytevector-set!-check? 8 v i)
           (begin
             (unless (fill? fill) (invalid-value who fill))
             (#3%$bytevector-set! v i fill))
-          (if (bytevector? v)
+          (if (mutable-bytevector? v)
               (invalid-index who v i)
-              (not-a-bytevector who v)))))
+              (not-a-mutable-bytevector who v)))))
 
   (set-who! bytevector-s16-native-ref
     (lambda (v i)
@@ -561,24 +579,24 @@
   (set-who! bytevector-s16-native-set!
     (let ([value-okay? (signed-value-pred 16)])
       (lambda (v i k)
-        (if ($bytevector-ref-check? 16 v i)
+        (if ($bytevector-set!-check? 16 v i)
             (begin
               (unless (value-okay? k) (invalid-value who k))
               (#3%bytevector-s16-native-set! v i k))
-            (if (bytevector? v)
+            (if (mutable-bytevector? v)
                 (invalid-index who v i)
-                (not-a-bytevector who v))))))
+                (not-a-mutable-bytevector who v))))))
 
   (set-who! bytevector-u16-native-set!
     (let ([value-okay? (unsigned-value-pred 16)])
       (lambda (v i k)
-        (if ($bytevector-ref-check? 16 v i)
+        (if ($bytevector-set!-check? 16 v i)
             (begin
               (unless (value-okay? k) (invalid-value who k))
               (#3%bytevector-u16-native-set! v i k))
-            (if (bytevector? v)
+            (if (mutable-bytevector? v)
                 (invalid-index who v i)
-                (not-a-bytevector who v))))))
+                (not-a-mutable-bytevector who v))))))
 
   (set-who! bytevector-s32-native-ref
     (lambda (v i)
@@ -599,24 +617,24 @@
   (set-who! bytevector-s32-native-set!
     (let ([value-okay? (signed-value-pred 32)])
       (lambda (v i k)
-        (if ($bytevector-ref-check? 32 v i)
+        (if ($bytevector-set!-check? 32 v i)
             (begin
               (unless (value-okay? k) (invalid-value who k))
               (#3%bytevector-s32-native-set! v i k))
-            (if (bytevector? v)
+            (if (mutable-bytevector? v)
                 (invalid-index who v i)
-                (not-a-bytevector who v))))))
+                (not-a-mutable-bytevector who v))))))
 
   (set-who! bytevector-u32-native-set!
     (let ([value-okay? (unsigned-value-pred 32)])
       (lambda (v i k)
-        (if ($bytevector-ref-check? 32 v i)
+        (if ($bytevector-set!-check? 32 v i)
             (begin
               (unless (value-okay? k) (invalid-value who k))
               (#3%bytevector-u32-native-set! v i k))
-            (if (bytevector? v)
+            (if (mutable-bytevector? v)
                 (invalid-index who v i)
-                (not-a-bytevector who v))))))
+                (not-a-mutable-bytevector who v))))))
 
   (set-who! bytevector-s64-native-ref
     (lambda (v i)
@@ -655,7 +673,7 @@
   (set-who! bytevector-s64-native-set!
     (let ([value-okay? (signed-value-pred 64)])
       (lambda (v i k)
-        (if ($bytevector-ref-check? 64 v i)
+        (if ($bytevector-set!-check? 64 v i)
             (begin
               (unless (value-okay? k) (invalid-value who k))
               (constant-case ptr-bits
@@ -668,14 +686,14 @@
                    [(little)
                     (#3%bytevector-s32-native-set! v (fx+ i 4) (ash k -32))
                     (#3%bytevector-u32-native-set! v i (logand k (- (expt 2 32) 1)))])]))
-            (if (bytevector? v)
+            (if (mutable-bytevector? v)
                 (invalid-index who v i)
-                (not-a-bytevector who v))))))
+                (not-a-mutable-bytevector who v))))))
 
   (set-who! bytevector-u64-native-set!
     (let ([value-okay? (unsigned-value-pred 64)])
       (lambda (v i k)
-        (if ($bytevector-ref-check? 64 v i)
+        (if ($bytevector-set!-check? 64 v i)
             (begin
               (unless (value-okay? k) (invalid-value who k))
               (constant-case ptr-bits
@@ -688,9 +706,9 @@
                    [(little)
                     (#3%bytevector-u32-native-set! v (fx+ i 4) (ash k -32))
                     (#3%bytevector-u32-native-set! v i (logand k (- (expt 2 32) 1)))])]))
-            (if (bytevector? v)
+            (if (mutable-bytevector? v)
                 (invalid-index who v i)
-                (not-a-bytevector who v))))))
+                (not-a-mutable-bytevector who v))))))
 
   (set-who! bytevector-ieee-single-native-ref
     (lambda (v i)
@@ -710,21 +728,21 @@
 
   (set-who! bytevector-ieee-single-native-set!
     (lambda (v i x)
-      (if ($bytevector-ref-check? 32 v i)
+      (if ($bytevector-set!-check? 32 v i)
          ; inline routine checks to make sure x is a real number
           (#3%bytevector-ieee-single-native-set! v i x)
-          (if (bytevector? v)
+          (if (mutable-bytevector? v)
               (invalid-index who v i)
-              (not-a-bytevector who v)))))
+              (not-a-mutable-bytevector who v)))))
 
   (set-who! bytevector-ieee-double-native-set!
     (lambda (v i x)
-      (if ($bytevector-ref-check? 64 v i)
+      (if ($bytevector-set!-check? 64 v i)
          ; inline routine checks to make sure x is a real number
           (#3%bytevector-ieee-double-native-set! v i x)
-          (if (bytevector? v)
+          (if (mutable-bytevector? v)
               (invalid-index who v i)
-              (not-a-bytevector who v)))))
+              (not-a-mutable-bytevector who v)))))
 
   (set-who! bytevector-copy
     (lambda (v)
@@ -740,7 +758,7 @@
   (set-who! bytevector-copy!
     (lambda (v1 i1 v2 i2 k)
       (unless (bytevector? v1) (not-a-bytevector who v1))
-      (unless (bytevector? v2) (not-a-bytevector who v2))
+      (unless (mutable-bytevector? v2) (not-a-mutable-bytevector who v2))
       (let ([n1 (bytevector-length v1)] [n2 (bytevector-length v2)])
         (unless (and (fixnum? i1) (fx>= i1 0))
           ($oops who "invalid start value ~s" i1))
@@ -754,10 +772,22 @@
           ($oops who "index ~s + count ~s is beyond the end of ~s" i2 k v2))
        ; whew!
         (#3%bytevector-copy! v1 i1 v2 i2 k))))
+  
+  (set-who! bytevector->immutable-bytevector
+    (lambda (v)
+      (unless (bytevector? v)
+        ($oops who "~s is not a bytevector" v))
+      (cond
+        [(immutable-bytevector? v) v]
+        [(fx= 0 (bytevector-length v)) ($tc-field 'null-immutable-bytevector ($tc))]
+        [else
+         (let ([v2 (bytevector-copy v)])
+           ($bytevector-set-immutable! v2)
+           v2)])))
 
   (set-who! bytevector-fill!
     (lambda (v fill)
-      (unless (bytevector? v) (not-a-bytevector who v))
+      (unless (mutable-bytevector? v) (not-a-mutable-bytevector who v))
       (unless (fill? fill) (invalid-fill-value who fill))
       (#3%bytevector-fill! v fill)))
 
@@ -777,6 +807,16 @@
         [(64) (#2%$bytevector-ref-check? 64 v i)]
         [else ($oops who "invalid bits argument ~s" bits)])))
 
+  (set-who! $bytevector-set!-check?
+    (lambda (bits v i)
+     ; inlined handles only constant bits argument
+      (case bits
+        [(8) (#2%$bytevector-set!-check? 8 v i)]
+        [(16) (#2%$bytevector-set!-check? 16 v i)]
+        [(32) (#2%$bytevector-set!-check? 32 v i)]
+        [(64) (#2%$bytevector-set!-check? 64 v i)]
+        [else ($oops who "invalid bits argument ~s" bits)])))
+
   (set-who! bytevector-s16-ref
     (lambda (v i eness)
       ($bytevector-s16-ref v i eness who)))
@@ -985,7 +1025,7 @@
           (bytevector-u8-set! v (fx+ i 1) (bytevector-u8-ref v2 1))
           (bytevector-u8-set! v (fx+ i 2) (bytevector-u8-ref v2 2))
           (bytevector-u8-set! v (fx+ i 3) (bytevector-u8-ref v2 3))))
-      (unless (bytevector? v) (not-a-bytevector who v))
+      (unless (mutable-bytevector? v) (not-a-mutable-bytevector who v))
       (unaligned-ref-check who 4 v i)
       (let ([x ($real->flonum x who)])
         (if (or (constant unaligned-floats) (fx= (fxlogand i 3) 0))
@@ -1028,7 +1068,7 @@
           (bytevector-u8-set! v (fx+ i 5) (bytevector-u8-ref v2 5))
           (bytevector-u8-set! v (fx+ i 6) (bytevector-u8-ref v2 6))
           (bytevector-u8-set! v (fx+ i 7) (bytevector-u8-ref v2 7))))
-      (unless (bytevector? v) (not-a-bytevector who v))
+      (unless (mutable-bytevector? v) (not-a-mutable-bytevector who v))
       (unaligned-ref-check who 8 v i)
       (let ([x ($real->flonum x who)])
         (if (or (constant unaligned-floats) (fx= (fxlogand i 7) 0))
@@ -1102,26 +1142,26 @@
     (define $bytevector-s8-set!
       (let ([value-okay? (signed-value-pred 8)])
         (lambda (v i k eness who)
-          (if ($bytevector-ref-check? 8 v i)
+          (if ($bytevector-set!-check? 8 v i)
               (begin
                 (unless (value-okay? k) (invalid-value who k))
                 (unless (memq eness '(little big)) (unrecognized-endianness who eness))
                 (#3%bytevector-s8-set! v i k))
-              (if (bytevector? v)
+              (if (mutable-bytevector? v)
                   (invalid-index who v i)
-                  (not-a-bytevector who v))))))
+                  (not-a-mutable-bytevector who v))))))
 
     (define $bytevector-u8-set!
       (let ([value-okay? (unsigned-value-pred 8)])
         (lambda (v i k eness who)
-          (if ($bytevector-ref-check? 8 v i)
+          (if ($bytevector-set!-check? 8 v i)
               (begin
                 (unless (value-okay? k) (invalid-value who k))
                 (unless (memq eness '(little big)) (unrecognized-endianness who eness))
                 (#3%bytevector-u8-set! v i k))
-              (if (bytevector? v)
+              (if (mutable-bytevector? v)
                   (invalid-index who v i)
-                  (not-a-bytevector who v))))))
+                  (not-a-mutable-bytevector who v))))))
 
     (set-who! bytevector-sint-set!
       (lambda (v i k eness size)
@@ -1131,7 +1171,7 @@
           [(4) ($bytevector-s32-set! v i k eness who)]
           [(8) ($bytevector-s64-set! v i k eness who)]
           [else
-           (unless (bytevector? v) (not-a-bytevector who v))
+           (unless (mutable-bytevector? v) (not-a-mutable-bytevector who v))
            (unless (and (fixnum? size) (fx> size 0)) (invalid-size who size))
            (unaligned-ref-check who size v i)
            (unless (and (or (fixnum? k) (bignum? k))
@@ -1151,7 +1191,7 @@
           [(4) ($bytevector-u32-set! v i k eness who)]
           [(8) ($bytevector-u64-set! v i k eness who)]
           [else
-           (unless (bytevector? v) (not-a-bytevector who v))
+           (unless (mutable-bytevector? v) (not-a-mutable-bytevector who v))
            (unless (and (fixnum? size) (fx> size 0)) (invalid-size who size))
            (unaligned-ref-check who size v i)
            (unless (and (or (fixnum? k) (bignum? k))
diff --git a/s/cmacros.ss b/s/cmacros.ss
index 0da94eed1f..91646488a4 100644
--- a/s/cmacros.ss
+++ b/s/cmacros.ss
@@ -449,6 +449,12 @@
 (define-constant fasl-type-visit 34)
 (define-constant fasl-type-revisit 35)
 
+(define-constant fasl-type-immutable-vector 36)
+(define-constant fasl-type-immutable-string 37)
+(define-constant fasl-type-immutable-fxvector 38)
+(define-constant fasl-type-immutable-bytevector 39)
+(define-constant fasl-type-immutable-box 40)
+
 (define-constant fasl-fld-ptr 0)
 (define-constant fasl-fld-u8 1)
 (define-constant fasl-fld-i16 2)
@@ -714,7 +720,8 @@
 (define-constant type-ratnum           #b00010110) ; bit 4 set for non-bignum numbers
 (define-constant type-inexactnum       #b00110110)
 (define-constant type-exactnum         #b01010110)
-(define-constant type-box              #b00001110) ; bit 3 set for non-numbers
+(define-constant type-box               #b0001110) ; bit 3 set for non-numbers
+(define-constant type-immutable-box    #b10001110) ; low 7 bits match `type-box`
 (define-constant type-port             #b00011110)
 ; #b00101110 (forward_marker) must not be used
 (define-constant type-code             #b00111110)
@@ -738,10 +745,14 @@
 
 (define-constant fixnum-offset (- (constant ptr-bits) (constant fixnum-bits)))
 
-(define-constant string-length-offset      3)
+; string length field (high bits) + immutabilty is stored with type
+(define-constant string-length-offset      4)
+(define-constant string-immutable-flag
+  (expt 2 (- (constant string-length-offset) 1)))
 (define-constant iptr maximum-string-length
   (min (- (expt 2 (fx- (constant ptr-bits) (constant string-length-offset))) 1)
        (constant most-positive-fixnum)))
+
 (define-constant bignum-sign-offset        5)
 (define-constant bignum-length-offset      6)
 (define-constant iptr maximum-bignum-length
@@ -750,20 +761,26 @@
 (define-constant bigit-bits                32)
 (define-constant bigit-bytes               (/ (constant bigit-bits) 8))
 
-; vector length field is a fixnum
-(define-constant vector-length-offset (constant fixnum-offset))
+; vector length field is a fixnum shifted by 1 for immutability bit
+(define-constant vector-length-offset (fx+ 1 (constant fixnum-offset)))
+(define-constant vector-immutable-flag
+  (expt 2 (- (constant vector-length-offset) 1)))
 (define-constant iptr maximum-vector-length
   (min (- (expt 2 (fx- (constant ptr-bits) (constant vector-length-offset))) 1)
        (constant most-positive-fixnum)))
 
-; fxvector length field is stored with type
-(define-constant fxvector-length-offset 3)
+; fxvector length field (high bits) + immutabilty is stored with type
+(define-constant fxvector-length-offset 4)
+(define-constant fxvector-immutable-flag
+  (expt 2 (- (constant fxvector-length-offset) 1)))
 (define-constant iptr maximum-fxvector-length
   (min (- (expt 2 (fx- (constant ptr-bits) (constant fxvector-length-offset))) 1)
        (constant most-positive-fixnum)))
 
-; bytevector length field is stored with type
-(define-constant bytevector-length-offset 3)
+; bytevector length field (high bits) + immutabilty is stored with type
+(define-constant bytevector-length-offset 4)
+(define-constant bytevector-immutable-flag
+  (expt 2 (- (constant bytevector-length-offset) 1)))
 (define-constant iptr maximum-bytevector-length
   (min (- (expt 2 (fx- (constant ptr-bits) (constant bytevector-length-offset))) 1)
           (constant most-positive-fixnum)))
@@ -870,7 +887,7 @@
   (fxlogor (fxsll (constant port-flag-binary) (constant port-flags-offset))
            (constant mask-output-port)))
 (define-constant mask-textual-output-port (constant mask-binary-output-port))
-(define-constant mask-box          (constant byte-constant-mask))
+(define-constant mask-box                #x7F)
 (define-constant mask-code               #xFF)
 (define-constant mask-system-code
   (fxlogor (fxsll (constant code-flag-system) (constant code-flags-offset))
@@ -883,6 +900,31 @@
 
 (define-constant mask-positive-fixnum #x80000003)
 
+(define-constant type-mutable-vector (constant type-vector))
+(define-constant type-immutable-vector
+  (fxior (constant type-vector) (constant vector-immutable-flag)))
+(define-constant mask-mutable-vector
+  (logior (constant mask-vector) (constant vector-immutable-flag)))
+(define-constant type-mutable-string (constant type-string))
+(define-constant type-immutable-string
+  (fxior (constant type-string) (constant string-immutable-flag)))
+(define-constant mask-mutable-string
+  (logior (constant mask-string) (constant string-immutable-flag)))
+(define-constant type-mutable-fxvector (constant type-fxvector))
+(define-constant type-immutable-fxvector
+  (fxior (constant type-fxvector) (constant fxvector-immutable-flag)))
+(define-constant mask-mutable-fxvector
+  (logior (constant mask-fxvector) (constant fxvector-immutable-flag)))
+(define-constant type-mutable-bytevector (constant type-bytevector))
+(define-constant type-immutable-bytevector
+  (fxior (constant type-bytevector) (constant fxvector-immutable-flag)))
+(define-constant mask-mutable-bytevector
+  (logior (constant mask-bytevector) (constant bytevector-immutable-flag)))
+
+(define-constant type-mutable-box (constant type-box))
+(define-constant mask-mutable-box (constant byte-constant-mask))
+(define-constant mask-immutable-box (constant byte-constant-mask))
+
 (define-constant fixnum-factor        (expt 2 (constant fixnum-offset)))
 (define-constant vector-length-factor (expt 2 (constant vector-length-offset)))
 (define-constant string-length-factor (expt 2 (constant string-length-offset)))
@@ -1291,6 +1333,10 @@
    [ptr target-machine]
    [ptr fxlength-bv]
    [ptr fxfirst-bit-set-bv]
+   [ptr null-immutable-vector]
+   [ptr null-immutable-fxvector]
+   [ptr null-immutable-bytevector]
+   [ptr null-immutable-string]
    [ptr meta-level]
    [ptr compile-profile]
    [ptr generate-inspector-information]
@@ -2260,6 +2306,7 @@
      (car #f 1 #t #t)
      (cdr #f 1 #t #t)
      (unbox #f 1 #t #t)
+     (set-box! #f 2 #t #t)
      (= #f 2 #f #t)
      (< #f 2 #f #t)
      (> #f 2 #f #t)
diff --git a/s/cpnanopass.ss b/s/cpnanopass.ss
index df71d247ab..833e1fe6d1 100644
--- a/s/cpnanopass.ss
+++ b/s/cpnanopass.ss
@@ -3560,7 +3560,7 @@
                   (%inline logor ,e (immediate ,type))))))
         (define-syntax build-ref-check
           (syntax-rules ()
-            [(_ type-disp maximum-length length-offset type mask)
+            [(_ type-disp maximum-length length-offset type mask full-mask)
              (lambda (e-v e-i maybe-e-new)
                ; NB: caller must bind e-v, e-i, and maybe-e-new
                (safe-assert (no-need-to-bind? #t e-v))
@@ -3582,7 +3582,7 @@
                                 (%type-check mask type ,t)
                                 (if maybe-e-new (build-and e (build-fixnums? (list maybe-e-new))) e)))))]
                      [else
-                      (let ([e (%inline u< ,e-i ,(extract-length t (constant type) (constant length-offset)))])
+                      (let ([e (%inline u< ,e-i ,(extract-length t (constant full-mask) (constant length-offset)))])
                         (if (and (eqv? (constant type) (constant type-fixnum))
                                  (eqv? (constant mask) (constant mask-fixnum)))
                             (build-and e (build-fixnums? (if maybe-e-new (list e-i t maybe-e-new) (list e-i t))))
@@ -3591,6 +3591,15 @@
                               (build-and
                                 (build-fixnums? (if maybe-e-new (list e-i maybe-e-new) (list e-i)))
                                 e))))]))))]))
+        (define-syntax build-set-immutable!
+          (syntax-rules ()
+            [(_ type-disp immutable-flag)
+             (lambda (e-v)
+               (bind #t (e-v)
+                     `(set! ,(%mref ,e-v ,(constant type-disp))
+                       ,(%inline logor
+                                 ,(%mref ,e-v ,(constant type-disp))
+                                 (immediate ,(constant immutable-flag))))))]))
         (define inline-args-limit 10)
         (define reduce-equality
           (lambda (src sexpr moi e1 e2 e*)
@@ -4645,9 +4654,13 @@
           (typed-object-pred bignum? mask-bignum type-bignum)
           (typed-object-pred box? mask-box type-box)
           (typed-object-pred bytevector? mask-bytevector type-bytevector)
+          (typed-object-pred mutable-bytevector? mask-mutable-bytevector type-mutable-bytevector)
+          (typed-object-pred immutable-bytevector? mask-mutable-bytevector type-immutable-bytevector)
           (typed-object-pred $code? mask-code type-code)
           (typed-object-pred $exactnum? mask-exactnum type-exactnum)
           (typed-object-pred fxvector? mask-fxvector type-fxvector)
+          (typed-object-pred mutable-fxvector? mask-mutable-fxvector type-mutable-fxvector)
+          (typed-object-pred immutable-fxvector? mask-mutable-fxvector type-immutable-fxvector)
           (typed-object-pred $inexactnum? mask-inexactnum type-inexactnum)
           (typed-object-pred $rtd-counts? mask-rtd-counts type-rtd-counts)
           (typed-object-pred input-port? mask-input-port type-input-port)
@@ -4656,9 +4669,13 @@
           (typed-object-pred ratnum? mask-ratnum type-ratnum)
           (typed-object-pred $record? mask-record type-record)
           (typed-object-pred string? mask-string type-string)
+          (typed-object-pred mutable-string? mask-mutable-string type-mutable-string)
+          (typed-object-pred immutable-string? mask-mutable-string type-immutable-string)
           (typed-object-pred $system-code? mask-system-code type-system-code)
           (typed-object-pred $tlc? mask-tlc type-tlc)
           (typed-object-pred vector? mask-vector type-vector)
+          (typed-object-pred mutable-vector? mask-mutable-vector type-mutable-vector)
+          (typed-object-pred immutable-vector? mask-mutable-vector type-immutable-vector)
           (typed-object-pred thread? mask-thread type-thread))
         (define-inline 3 $bigpositive?
           [(e) (%type-check mask-signed-bignum type-positive-bignum
@@ -4729,6 +4746,14 @@
                  (set! ,(%mref ,t ,(constant box-type-disp)) ,(%constant type-box))
                  (set! ,(%mref ,t ,(constant box-ref-disp)) ,e)
                  ,t)))])
+        (define-inline 2 box-immutable
+          [(e)
+           (bind #f (e)
+             (bind #t ([t (%constant-alloc type-typed-object (constant size-box))])
+               (%seq
+                 (set! ,(%mref ,t ,(constant box-type-disp)) ,(%constant type-immutable-box))
+                 (set! ,(%mref ,t ,(constant box-ref-disp)) ,e)
+                 ,t)))])
         (define-inline 3 $make-tlc
           [(e-ht e-keyval e-next)
            (bind #f (e-ht e-keyval e-next)
@@ -4921,31 +4946,31 @@
         (let ()
           (define-syntax def-len
             (syntax-rules ()
-              [(_ prim mask type type-disp length-offset)
+              [(_ prim full-mask type type-disp length-offset)
                (define-inline 3 prim
-                 [(e) (extract-length (%mref ,e ,(constant type-disp)) (constant type) (constant length-offset))])]))
-          (def-len vector-length mask-vector type-vector vector-type-disp vector-length-offset)
-          (def-len fxvector-length mask-fxvector type-fxvector fxvector-type-disp fxvector-length-offset)
-          (def-len string-length mask-string type-string string-type-disp string-length-offset)
-          (def-len bytevector-length mask-bytevector type-bytevector bytevector-type-disp bytevector-length-offset)
+                 [(e) (extract-length (%mref ,e ,(constant type-disp)) (constant full-mask) (constant length-offset))])]))
+          (def-len vector-length mask-mutable-vector type-vector vector-type-disp vector-length-offset)
+          (def-len fxvector-length mask-mutable-fxvector type-fxvector fxvector-type-disp fxvector-length-offset)
+          (def-len string-length mask-mutable-string type-string string-type-disp string-length-offset)
+          (def-len bytevector-length mask-mutable-bytevector type-bytevector bytevector-type-disp bytevector-length-offset)
           (def-len $bignum-length mask-bignum type-bignum bignum-type-disp bignum-length-offset))
         (let ()
           (define-syntax def-len
             (syntax-rules ()
-              [(_ prim mask type type-disp length-offset)
+              [(_ prim mask full-mask type type-disp length-offset)
                (define-inline 2 prim
                  [(e) (let ([Lerr (make-local-label 'Lerr)])
                         (bind #t (e)
                           `(if ,(%type-check mask-typed-object type-typed-object ,e)
                                ,(bind #t ([t/l (%mref ,e ,(constant type-disp))])
                                   `(if ,(%type-check mask type ,t/l)
-                                       ,(extract-length t/l (constant type) (constant length-offset))
+                                       ,(extract-length t/l (constant full-mask) (constant length-offset))
                                        (goto ,Lerr)))
                                (label ,Lerr ,(build-libcall #t #f sexpr prim e)))))])]))
-          (def-len vector-length mask-vector type-vector vector-type-disp vector-length-offset)
-          (def-len fxvector-length mask-fxvector type-fxvector fxvector-type-disp fxvector-length-offset)
-          (def-len string-length mask-string type-string string-type-disp string-length-offset)
-          (def-len bytevector-length mask-bytevector type-bytevector bytevector-type-disp bytevector-length-offset))
+          (def-len vector-length mask-vector mask-mutable-vector type-vector vector-type-disp vector-length-offset)
+          (def-len fxvector-length mask-fxvector mask-mutable-fxvector type-fxvector fxvector-type-disp fxvector-length-offset)
+          (def-len string-length mask-string mask-mutable-string type-string string-type-disp string-length-offset)
+          (def-len bytevector-length mask-bytevector mask-mutable-bytevector type-bytevector bytevector-type-disp bytevector-length-offset))
         ; TODO: consider adding integer?, integer-valued?, rational?, rational-valued?,
         ; real?, and real-valued?
         (let ()
@@ -4964,6 +4989,12 @@
             [(e) (build-number? e)])
           (define-inline 2 complex?
             [(e) (build-number? e)]))
+        (define-inline 3 mutable-box?
+          [(e) (bind #t (e)
+                 (%typed-object-check mask-immutable-box type-mutable-box ,e))])
+        (define-inline 3 immutable-box?
+          [(e) (bind #t (e)
+                 (%typed-object-check mask-immutable-box type-immutable-box ,e))])
         (define-inline 3 set-car!
           [(e1 e2) (build-dirty-store e1 (constant pair-car-disp) e2)])
         (define-inline 3 set-cdr!
@@ -4980,11 +5011,10 @@
           [(e1 e2) (build-dirty-store e1 (constant port-info-disp) e2)])
         (define-inline 3 set-port-name!
           [(e1 e2) (build-dirty-store e1 (constant port-name-disp) e2)])
-        ; TODO: requires set-box! library routine
-        #;(define-inline 2 set-box!
+        (define-inline 2 set-box!
           [(e-box e-new)
            (bind #t (e-box e-new)
-             `(if ,(%typed-object-check mask-box type-box ,e-box)
+             `(if ,(%typed-object-check mask-mutable-box type-box ,e-box)
                   ,(build-dirty-store e-box (constant box-ref-disp) e-new)
                   ,(build-libcall #t src sexpr set-box! e-box e-new)))])
         (define-inline 2 set-car!
@@ -7646,9 +7676,14 @@
                 [(e-name e-handler e-ib e-ob) (go e-name e-handler e-ib e-ob `(quote #f))]
                 [(e-name e-handler e-ib e-ob e-info) (go e-name e-handler e-ib e-ob e-info)]))))
         (let ()
-          (define build-fxvector-ref-check (build-ref-check fxvector-type-disp maximum-fxvector-length fxvector-length-offset type-fxvector mask-fxvector))
+          (define build-fxvector-ref-check (build-ref-check fxvector-type-disp maximum-fxvector-length fxvector-length-offset
+                                                            type-fxvector mask-fxvector mask-mutable-fxvector))
+          (define build-fxvector-set!-check (build-ref-check fxvector-type-disp maximum-fxvector-length fxvector-length-offset
+                                                             type-mutable-fxvector mask-mutable-fxvector mask-mutable-fxvector))
           (define-inline 2 $fxvector-ref-check?
             [(e-fv e-i) (bind #t (e-fv e-i) (build-fxvector-ref-check e-fv e-i #f))])
+          (define-inline 2 $fxvector-set!-check?
+            [(e-fv e-i) (bind #t (e-fv e-i) (build-fxvector-set!-check e-fv e-i #f))])
           (let ()
             (define (go e-fv e-i)
               (cond
@@ -7681,15 +7716,26 @@
            (define-inline 2 fxvector-set!
              [(e-fv e-i e-new)
               (bind #t (e-fv e-i e-new)
-                `(if ,(build-fxvector-ref-check e-fv e-i e-new)
+                `(if ,(build-fxvector-set!-check e-fv e-i e-new)
                      ,(go e-fv e-i e-new)
-                     ,(build-libcall #t src sexpr fxvector-set! e-fv e-i e-new)))])))
+                     ,(build-libcall #t src sexpr fxvector-set! e-fv e-i e-new)))])
+          (define-inline 3 $fxvector-set-immutable!
+            [(e-fv) ((build-set-immutable! fxvector-type-disp fxvector-immutable-flag) e-fv)])))
         (let ()
           (define build-string-ref-check
             (lambda (e-s e-i)
-              ((build-ref-check string-type-disp maximum-string-length string-length-offset type-string mask-string) e-s e-i #f)))
+              ((build-ref-check string-type-disp maximum-string-length string-length-offset
+                                type-string mask-string mask-mutable-string)
+               e-s e-i #f)))
+          (define build-string-set!-check
+            (lambda (e-s e-i)
+              ((build-ref-check string-type-disp maximum-string-length string-length-offset
+                                type-mutable-string mask-mutable-string mask-mutable-string)
+               e-s e-i #f)))
           (define-inline 2 $string-ref-check?
             [(e-s e-i) (bind #t (e-s e-i) (build-string-ref-check e-s e-i))])
+          (define-inline 2 $string-set!-check?
+            [(e-s e-i) (bind #t (e-s e-i) (build-string-set!-check e-s e-i))])
           (let ()
             (define (go e-s e-i)
               (cond
@@ -7731,16 +7777,25 @@
             (define-inline 2 string-set!
               [(e-s e-i e-new)
                (bind #t (e-s e-i e-new)
-                 `(if ,(let ([e-ref-check (build-string-ref-check e-s e-i)])
+                 `(if ,(let ([e-ref-check (build-string-set!-check e-s e-i)])
                          (if (constant? char? e-new)
                              e-ref-check
                              (build-and e-ref-check (%type-check mask-char type-char ,e-new))))
                       ,(go e-s e-i e-new)
-                      ,(build-libcall #t src sexpr string-set! e-s e-i e-new)))])))
+                      ,(build-libcall #t src sexpr string-set! e-s e-i e-new)))])
+            (define-inline 3 $string-set-immutable!
+              [(e-s) ((build-set-immutable! string-type-disp string-immutable-flag) e-s)])))
         (let ()
-          (define build-vector-ref-check (build-ref-check vector-type-disp maximum-vector-length vector-length-offset type-vector mask-vector))
+          (define build-vector-ref-check
+            (build-ref-check vector-type-disp maximum-vector-length vector-length-offset
+                             type-vector mask-vector mask-mutable-vector))
+          (define build-vector-set!-check
+            (build-ref-check vector-type-disp maximum-vector-length vector-length-offset
+                             type-mutable-vector mask-mutable-vector mask-mutable-vector))
           (define-inline 2 $vector-ref-check?
             [(e-v e-i) (bind #t (e-v e-i) (build-vector-ref-check e-v e-i #f))])
+          (define-inline 2 $vector-set!-check?
+            [(e-v e-i) (bind #t (e-v e-i) (build-vector-set!-check e-v e-i #f))])
           (let ()
             (define (go e-v e-i)
               (nanopass-case (L7 Expr) e-i
@@ -7768,9 +7823,11 @@
             (define-inline 2 vector-set!
               [(e-v e-i e-new)
                (bind #t (e-v e-i e-new)
-                 `(if ,(build-vector-ref-check e-v e-i #f)
+                 `(if ,(build-vector-set!-check e-v e-i #f)
                       ,(go e-v e-i e-new)
-                      ,(build-libcall #t src sexpr vector-set! e-v e-i e-new)))]))
+                      ,(build-libcall #t src sexpr vector-set! e-v e-i e-new)))])
+          (define-inline 3 $vector-set-immutable!
+            [(e-fv) ((build-set-immutable! vector-type-disp vector-immutable-flag) e-fv)]))
           (let ()
             (define (go e-v e-i e-new)
               `(set!
@@ -7785,41 +7842,52 @@
             (define-inline 2 vector-set-fixnum!
               [(e-v e-i e-new)
                (bind #t (e-v e-i e-new)
-                 `(if ,(build-vector-ref-check e-v e-i e-new)
+                 `(if ,(build-vector-set!-check e-v e-i e-new)
                       ,(go e-v e-i e-new)
                       ,(build-libcall #t src sexpr vector-set-fixnum! e-v e-i e-new)))])))
-        (define-inline 2 $bytevector-ref-check?
-          [(e-bits e-bv e-i)
-           (nanopass-case (L7 Expr) e-bits
-             [(quote ,d)
-              (guard (and (fixnum? d) (fx> d 0) (fx= (* (fxquotient d 8) 8) d)))
-              (let ([bits d] [bytes (fxquotient d 8)])
-                (bind #t (e-bv e-i)
-                  (build-and
-                    (%type-check mask-typed-object type-typed-object ,e-bv)
-                    (bind #t ([t (%mref ,e-bv ,(constant bytevector-type-disp))])
+          (let ()
+            (define build-bytevector-ref-check
+              (lambda (e-bits e-bv e-i check-mutable?)
+               (nanopass-case (L7 Expr) e-bits
+                 [(quote ,d)
+                  (guard (and (fixnum? d) (fx> d 0) (fx= (* (fxquotient d 8) 8) d)))
+                  (let ([bits d] [bytes (fxquotient d 8)])
+                    (bind #t (e-bv e-i)
                       (build-and
-                        (%type-check mask-bytevector type-bytevector ,t)
-                        (cond
-                          [(expr->index e-i bytes (constant maximum-bytevector-length)) =>
-                           (lambda (index)
-                             (%inline u<
-                               (immediate ,(logor (ash (+ index (fx- bytes 1)) (constant bytevector-length-offset))
-                                             (constant type-bytevector)))
-                               ,t))]
-                          [else
-                            (build-and
-                              ($type-check (fxlogor (fix (fx- bytes 1)) (constant mask-fixnum)) (constant type-fixnum) e-i)
-                              (%inline u<
-                                ; NB. add cannot overflow or change negative to positive when
-                                ; low-order (log2 bytes) bits of fixnum value are zero, as
-                                ; guaranteed by type-check above
-                                ,(if (fx= bytes 1)
-                                     e-i
-                                     (%inline + ,e-i (immediate ,(fix (fx- bytes 1)))))
-                                ,(extract-length t (constant type-bytevector) (constant bytevector-length-offset))))]))))))]
-             [(seq (profile ,src) ,[e]) (and e `(seq (profile ,src) ,e))]
-             [else #f])])
+                        (%type-check mask-typed-object type-typed-object ,e-bv)
+                        (bind #t ([t (%mref ,e-bv ,(constant bytevector-type-disp))])
+                          (build-and
+                            (if check-mutable?
+                                (%type-check mask-mutable-bytevector type-mutable-bytevector ,t)
+                                (%type-check mask-bytevector type-bytevector ,t))
+                            (cond
+                              [(expr->index e-i bytes (constant maximum-bytevector-length)) =>
+                               (lambda (index)
+                                 (%inline u<
+                                   (immediate ,(logor (ash (+ index (fx- bytes 1)) (constant bytevector-length-offset))
+                                                 (constant type-bytevector)))
+                                   ,t))]  
+                              [else
+                                (build-and
+                                  ($type-check (fxlogor (fix (fx- bytes 1)) (constant mask-fixnum)) (constant type-fixnum) e-i)
+                                  (%inline u<
+                                    ; NB. add cannot overflow or change negative to positive when
+                                    ; low-order (log2 bytes) bits of fixnum value are zero, as
+                                    ; guaranteed by type-check above
+                                    ,(if (fx= bytes 1)
+                                         e-i
+                                         (%inline + ,e-i (immediate ,(fix (fx- bytes 1)))))
+                                    ,(%inline logand
+                                       ,(translate t
+                                          (constant bytevector-length-offset)
+                                          (constant fixnum-offset))
+                                       (immediate ,(- (constant fixnum-factor))))))]))))))]
+                 [(seq (profile ,src) ,[e]) (and e `(seq (profile ,src) ,e))]
+                 [else #f])))
+            (define-inline 2 $bytevector-ref-check?
+              [(e-bits e-bv e-i) (build-bytevector-ref-check e-bits e-bv e-i #f)])
+            (define-inline 2 $bytevector-set!-check?
+              [(e-bits e-bv e-i) (build-bytevector-ref-check e-bits e-bv e-i #t)]))
         (let ()
           (define build-bytevector-fill
             (let ([filler (make-build-fill 1 (constant bytevector-data-disp))])
@@ -7968,6 +8036,9 @@
                              (constant bytevector-length-offset)))
                         ,bv))))])
 
+        (define-inline 3 $bytevector-set-immutable!
+          [(bv) ((build-set-immutable! bytevector-type-disp bytevector-immutable-flag) bv)])
+
         (let ()
           (define bv-index-offset
             (lambda (offset-expr)
@@ -11982,19 +12053,21 @@
                   (set! ,%ac0 ,(%constant svoid))
                   (jump ,%ref-ret (,%ac0))))]
            [(bytevector=?)
-            (let ([bv1 (make-tmp 'bv1)] [bv2 (make-tmp 'bv2)] [idx (make-tmp 'idx)])
+            (let ([bv1 (make-tmp 'bv1)] [bv2 (make-tmp 'bv2)] [idx (make-tmp 'idx)] [len2 (make-tmp 'len2)])
               (let ([Ltop (make-local-label 'Ltop)] [Lfail (make-local-label 'Lfail)])
                 (define iptr-bytes (in-context Triv (%constant ptr-bytes)))
-                `(lambda ,(make-info "bytevector=?" '(2)) 0 (,bv1 ,bv2 ,idx)
+                `(lambda ,(make-info "bytevector=?" '(2)) 0 (,bv1 ,bv2 ,idx ,len2)
                    ,(%seq
                       (set! ,bv1 ,(make-arg-opnd 1))
                       (set! ,bv2 ,(make-arg-opnd 2))
-                      (set! ,idx ,(%mref ,bv1 ,(constant bytevector-type-disp)))
-                      (if ,(%inline eq?
-                             ,(%mref ,bv2 ,(constant bytevector-type-disp))
-                             ,idx)
+                      (set! ,idx ,(%inline srl
+                                    ,(%mref ,bv1 ,(constant bytevector-type-disp))
+                                    ,(%constant bytevector-length-offset)))
+                      (set! ,len2 ,(%inline srl
+                                     ,(%mref ,bv2 ,(constant bytevector-type-disp))
+                                     ,(%constant bytevector-length-offset)))
+                      (if ,(%inline eq? ,len2 ,idx)
                           ,(%seq
-                             (set! ,idx ,(%inline srl ,idx ,(%constant bytevector-length-offset)))
                              (label ,Ltop)
                              (if ,(%inline >= ,idx ,iptr-bytes)
                                  (if ,(%inline eq?
diff --git a/s/fasl.ss b/s/fasl.ss
index 0c37f1f160..15d7b2d8cb 100644
--- a/s/fasl.ss
+++ b/s/fasl.ss
@@ -247,12 +247,16 @@
 
 (define wrf-string
    (lambda (x p t a?)
-      (put-u8 p (constant fasl-type-string))
+      (put-u8 p (if (immutable-string? x)
+                    (constant fasl-type-immutable-string)
+                    (constant fasl-type-string)))
       (wrf-string-help x p)))
 
 (define wrf-vector
    (lambda (x p t a?)
-      (put-u8 p (constant fasl-type-vector))
+      (put-u8 p (if (immutable-vector? x)
+                    (constant fasl-type-immutable-vector)
+                    (constant fasl-type-vector)))
       (let ([n (vector-length x)]) 
          (put-uptr p n)
          (let wrf-vector-loop ([i 0])
@@ -262,7 +266,9 @@
 
 (define wrf-fxvector
   (lambda (x p t a?)
-    (put-u8 p (constant fasl-type-fxvector))
+    (put-u8 p (if (immutable-fxvector? x)
+                  (constant fasl-type-immutable-fxvector)
+                  (constant fasl-type-fxvector)))
     (let ([n (fxvector-length x)])
       (put-uptr p n)
       (let wrf-fxvector-loop ([i 0])
@@ -272,7 +278,9 @@
 
 (define wrf-bytevector
   (lambda (x p t a?)
-    (put-u8 p (constant fasl-type-bytevector))
+    (put-u8 p (if (immutable-bytevector? x)
+                  (constant fasl-type-immutable-bytevector)
+                  (constant fasl-type-bytevector)))
     (let ([n (bytevector-length x)])
       (put-uptr p n)
       (let wrf-bytevector-loop ([i 0])
@@ -457,7 +465,9 @@
 
 (define wrf-box
    (lambda (x p t a?)
-      (put-u8 p (constant fasl-type-box))
+      (put-u8 p (if (immutable-box? x)
+                    (constant fasl-type-immutable-box)
+                    (constant fasl-type-box)))
       (wrf (unbox x) p t a?)))
 
 (define wrf-ratnum
diff --git a/s/library.ss b/s/library.ss
index 286ff16a49..dc49e21c84 100644
--- a/s/library.ss
+++ b/s/library.ss
@@ -240,15 +240,27 @@
   (define string-oops
     (lambda (who x)
       ($oops who "~s is not a string" x)))
+  (define mutable-string-oops
+    (lambda (who x)
+      ($oops who "~s is not a mutable string" x)))
   (define vector-oops
     (lambda (who x)
       ($oops who "~s is not a vector" x)))
+  (define mutable-vector-oops
+    (lambda (who x)
+      ($oops who "~s is not a mutable vector" x)))
   (define fxvector-oops
     (lambda (who x)
       ($oops who "~s is not an fxvector" x)))
+  (define mutable-fxvector-oops
+    (lambda (who x)
+      ($oops who "~s is not a mutable fxvector" x)))
   (define bytevector-oops
     (lambda (who x)
       ($oops who "~s is not a bytevector" x)))
+  (define mutable-bytevector-oops
+    (lambda (who x)
+      ($oops who "~s is not a mutable bytevector" x)))
   (define index-oops
     (lambda (who x i)
       ($oops who "~s is not a valid index for ~s" i x)))
@@ -261,13 +273,13 @@
         (string-oops 'string-ref s)))
 
   (define-library-entry (string-set! s i c)
-    (if ($string-ref-check? s i)
+    (if ($string-set!-check? s i)
         (if (char? c)
             (string-set! s i c)
             (char-oops 'string-set! c))
-        (if (string? s)
+        (if (mutable-string? s)
             (index-oops 'string-set! s i)
-            (string-oops 'string-set! s))))
+            (mutable-string-oops 'string-set! s))))
 
   (define-library-entry (string-length s)
     (string-oops 'string-length s))
@@ -278,15 +290,15 @@
         (vector-oops 'vector-ref v)))
 
   (define-library-entry (vector-set! v i x)
-    (if (vector? v)
+    (if (mutable-vector? v)
         (index-oops 'vector-set! v i)
-        (vector-oops 'vector-set! v)))
+        (mutable-vector-oops 'vector-set! v)))
 
   (define-library-entry (vector-set-fixnum! v i x)
     (if (fixnum? x)
-        (if (vector? v)
+        (if (mutable-vector? v)
             (index-oops 'vector-set-fixnum! v i)
-            (vector-oops 'vector-set-fixnum! v))
+            (mutable-vector-oops 'vector-set-fixnum! v))
         ($oops 'vector-set-fixnum! "~s is not a fixnum" x)))
 
   (define-library-entry (vector-length v)
@@ -298,11 +310,11 @@
         (fxvector-oops 'fxvector-ref v)))
 
   (define-library-entry (fxvector-set! v i x)
-    (if (fxvector? v)
+    (if (mutable-fxvector? v)
         (if (and (fixnum? i) ($fxu< i (fxvector-length v)))
             (fixnum-oops 'fxvector-set! x)
             (index-oops 'fxvector-set! v i))
-        (fxvector-oops 'fxvector-set! v)))
+        (mutable-fxvector-oops 'fxvector-set! v)))
 
   (define-library-entry (fxvector-length v)
     (fxvector-oops 'fxvector-length v))
@@ -318,22 +330,22 @@
         (bytevector-oops 'bytevector-u8-ref v)))
 
   (define-library-entry (bytevector-s8-set! v i k)
-    (if ($bytevector-ref-check? 8 v i)
+    (if ($bytevector-set!-check? 8 v i)
         (if (and (fixnum? k) (fx<= -128 k 127))
             (bytevector-s8-set! v i k)
             ($oops 'bytevector-s8-set! "invalid value ~s" k))
-        (if (bytevector? v)
+        (if (mutable-bytevector? v)
             (index-oops 'bytevector-s8-set! v i)
-            (bytevector-oops 'bytevector-s8-set! v))))
+            (mutable-bytevector-oops 'bytevector-s8-set! v))))
 
   (define-library-entry (bytevector-u8-set! v i k)
-    (if ($bytevector-ref-check? 8 v i)
+    (if ($bytevector-set!-check? 8 v i)
         (if (and (fixnum? k) (fx<= 0 k 255))
             (bytevector-u8-set! v i k)
             ($oops 'bytevector-u8-set! "invalid value ~s" k))
-        (if (bytevector? v)
+        (if (mutable-bytevector? v)
             (index-oops 'bytevector-u8-set! v i)
-            (bytevector-oops 'bytevector-u8-set! v))))
+            (mutable-bytevector-oops 'bytevector-u8-set! v))))
 
   (define-library-entry (bytevector-length v)
     (bytevector-oops 'bytevector-length v))
@@ -401,6 +413,9 @@
 (define-library-entry (unbox x)
   ($oops 'unbox "~s is not a box" x))
 
+(define-library-entry (set-box! b v)
+  ($oops 'set-box! "~s is not a mutable box" b))
+
 (let ()
 (define (fxnonfixnum1 who x)
   ($oops who "~s is not a fixnum" x))
diff --git a/s/mkheader.ss b/s/mkheader.ss
index 5a952dd76b..14b2dc36c8 100644
--- a/s/mkheader.ss
+++ b/s/mkheader.ss
@@ -267,7 +267,7 @@
             (access "x" vector type)
             ($ vector-length-offset)))
         (defref Svector_ref vector data)
-
+        
         (def "Sfxvector_length(x)"
           (format "((iptr)((uptr)~a>>~d))"
             (access "x" fxvector type)
@@ -930,6 +930,23 @@
         (defref RPHEADERLIVEMASK rp-header livemask)
         (defref RPHEADERTOPLINK rp-header toplink)
 
+        (def "Svector_set_immutable(x)"
+          (format "~a |= ~d"
+            (access "x" vector type)
+            ($ vector-immutable-flag)))
+        (def "Sfxvector_set_immutable(x)"
+          (format "~a |= ~d"
+            (access "x" fxvector type)
+            ($ fxvector-immutable-flag)))
+        (def "Sbytevector_set_immutable(x)"
+          (format "~a |= ~d"
+            (access "x" bytevector type)
+            ($ bytevector-immutable-flag)))
+        (def "Sstring_set_immutable(x)"
+          (format "~a |= ~d"
+            (access "x" string type)
+            ($ string-immutable-flag)))
+
         (nl)
         (comment "machine types")
         (pr "#define machine_type_names ")
diff --git a/s/primdata.ss b/s/primdata.ss
index 58b6b6abe9..898531d98b 100644
--- a/s/primdata.ss
+++ b/s/primdata.ss
@@ -1131,6 +1131,7 @@
   (block-write [sig [(textual-output-port string) (textual-output-port string length) -> (void)]] [flags true])
   (box [sig [(ptr) -> (box)]] [flags unrestricted alloc])
   (box? [sig [(ptr) -> (boolean)]] [flags pure unrestricted mifoldable discard])
+  (box-immutable [sig [(ptr) -> (box)]] [flags unrestricted alloc])
   (break [sig [(ptr ...) -> (ptr ...)]] [flags])
   (bwp-object? [sig [(ptr) -> (boolean)]] [flags pure unrestricted mifoldable discard])
   (bytes-allocated [sig [() -> (uint)] [(ptr) -> (uint)] [(ptr maybe-sub-symbol) -> (uint)]] [flags alloc])
@@ -1138,6 +1139,7 @@
   (bytevector [sig [(u8/s8 ...) -> (bytevector)]] [flags alloc cp02])
   (bytevector->s8-list [sig [(bytevector) -> (list)]] [flags alloc])
   (bytevector-truncate! [sig [(bytevector length) -> (bytevector)]] [flags true])
+  (bytevector->immutable-bytevector [sig [(bytevector) -> (bytevector)]] [flags alloc discard])
   (bytevector-s24-ref [sig [(bytevector sub-index symbol) -> (s24)]] [flags true mifoldable discard])
   (bytevector-s24-set! [sig [(bytevector sub-index symbol s24) -> (void)]] [flags true])
   (bytevector-s40-ref [sig [(bytevector sub-index symbol) -> (s40)]] [flags true mifoldable discard])
@@ -1331,6 +1333,7 @@
   (fxvector->list [sig [(fxvector) -> (list)]] [flags alloc])
   (fxvector-copy [sig [(fxvector) -> (fxvector)]] [flags alloc])
   (fxvector-fill! [sig [(fxvector fixnum) -> (fxvector)]] [flags true])
+  (fxvector->immutable-fxvector [sig [(fxvector) -> (fxvector)]] [flags alloc discard])
   (fxvector-length [sig [(fxvector) -> (length)]] [flags pure mifoldable discard true])
   (fxvector-ref [sig [(fxvector sub-index) -> (fixnum)]] [flags mifoldable discard cp02])
   (fxvector-set! [sig [(fxvector sub-index fixnum) -> (void)]] [flags true])
@@ -1356,6 +1359,11 @@
   (hashtable-weak? [sig [(hashtable) -> (boolean)]] [flags pure mifoldable discard])
   (iconv-codec [feature iconv] [sig [(sub-string) -> (codec)]] [flags pure true])
   (ieee-environment [sig [() -> (environment)]] [flags unrestricted alloc])
+  (immutable-string? [sig [(ptr) -> (boolean)]] [flags pure unrestricted mifoldable discard])
+  (immutable-box? [sig [(ptr) -> (boolean)]] [flags pure unrestricted mifoldable discard])
+  (immutable-vector? [sig [(ptr) -> (boolean)]] [flags pure unrestricted mifoldable discard])
+  (immutable-fxvector? [sig [(ptr) -> (boolean)]] [flags pure unrestricted mifoldable discard])
+  (immutable-bytevector? [sig [(ptr) -> (boolean)]] [flags pure unrestricted mifoldable discard])
   (initial-bytes-allocated [sig [() -> (uint)]] [flags unrestricted alloc])
   (input-port-ready? [sig [(input-port) -> (boolean)]] [flags])
   (inspect [sig [(ptr) -> (void)]] [flags unrestricted])
@@ -1425,6 +1433,11 @@
   (merge! [sig [(procedure list list) -> (list)]] [flags true])
   (mkdir [sig [(pathname) (pathname sub-uint) -> (void)]] [flags])
   (multibyte->string [feature windows] [sig [(sub-uint bytevector) -> (string)]] [flags true discard])
+  (mutable-box? [sig [(ptr) -> (boolean)]] [flags pure unrestricted mifoldable discard])
+  (mutable-string? [sig [(ptr) -> (boolean)]] [flags pure unrestricted mifoldable discard])
+  (mutable-fxvector? [sig [(ptr) -> (boolean)]] [flags pure unrestricted mifoldable discard])
+  (mutable-bytevector? [sig [(ptr) -> (boolean)]] [flags pure unrestricted mifoldable discard])
+  (mutable-vector? [sig [(ptr) -> (boolean)]] [flags pure unrestricted mifoldable discard])
   (mutex-acquire [feature pthreads] [sig [(mutex) (mutex ptr) -> (ptr)]] [flags]) ; can return #f if optional block? arg is #f
   (mutex-release [feature pthreads] [sig [(mutex) -> (void)]] [flags true])
   (mutex? [feature pthreads] [sig [(ptr) -> (boolean)]] [flags pure unrestricted mifoldable discard])
@@ -1594,6 +1607,7 @@
   (string-ci>=? [sig [(string string ...) -> (boolean)]] [flags mifoldable discard ieee r5rs])  ; not restricted to 2+ arguments
   (string-ci>? [sig [(string string ...) -> (boolean)]] [flags mifoldable discard ieee r5rs])   ; not restricted to 2+ arguments
   (string-copy! [sig [(string sub-length string sub-length sub-length) -> (void)]] [flags true])
+  (string->immutable-string [sig [(string) -> (string)]] [flags alloc discard])
   (string-truncate! [sig [(string length) -> (string)]] [flags true])
   (strip-fasl-file [sig [(pathname pathname fasl-strip-options) -> (void)]] [flags true])
   (sub1 [sig [(number) -> (number)]] [flags arith-op mifoldable discard])
@@ -1648,6 +1662,7 @@
   (utf-16le-codec [sig [() -> (codec)]] [flags pure unrestricted true])
   (utf-16be-codec [sig [() -> (codec)]] [flags pure unrestricted true])
   (vector-copy [sig [(vector) -> (vector)]] [flags alloc])
+  (vector->immutable-vector [sig [(vector) -> (vector)]] [flags alloc discard])
   (vector-set-fixnum! [sig [(vector sub-index fixnum) -> (void)]] [flags true])
   (virtual-register [sig [(sub-index) -> (ptr)]] [flags discard])
   (virtual-register-count [sig [() -> (length)]] [flags pure unrestricted true cp02])
@@ -1681,7 +1696,9 @@
   ($build-invoke-program [flags])
   ($byte-copy! [flags])
   ($bytevector-ref-check? [flags])
+  ($bytevector-set!-check? [flags])
   ($bytevector-set! [flags])
+  ($bytevector-set-immutable! [sig [(bytevector) -> (ptr)]] [flags true])
   ($capture-fasl-target [flags])
   ($c-error [flags])
   ($check-heap-errors [flags])
@@ -1935,6 +1952,8 @@
   ($fx+? [flags])
   ($fxu< [flags pure cp02])
   ($fxvector-ref-check? [flags])
+  ($fxvector-set!-check? [flags])
+  ($fxvector-set-immutable! [sig [(fxvector) -> (ptr)]] [flags true])
   ($gc-cpu-time [flags true])
   ($gc-real-time [flags true])
   ($gensym->pretty-name [flags])
@@ -2128,6 +2147,8 @@
   ($sremprop [flags])
   ($string-char-foldcase [flags])
   ($string-ref-check? [flags])
+  ($string-set!-check? [flags])
+  ($string-set-immutable! [sig [(string) -> (ptr)]] [flags true])
   ($str->num [flags])
   ($subsequent? [flags])
   ($swap-object-ref [flags]) ; can't fold since optimize-level 2 version does no checks
@@ -2174,6 +2195,8 @@
   ($untrace [flags])
   ($unwrap-ftype-pointer [flags])
   ($vector-ref-check? [flags])
+  ($vector-set!-check? [flags])
+  ($vector-set-immutable! [sig [(vector) -> (ptr)]] [flags true])
   ($verify-ftype-address [flags cp02])
   ($verify-ftype-pointer [flags])
   ($visit [flags])
diff --git a/s/prims.ss b/s/prims.ss
index a4860ca5cf..1942a6bd35 100644
--- a/s/prims.ss
+++ b/s/prims.ss
@@ -255,13 +255,13 @@
 )
 
 (define-who (bytevector-truncate! bv n)
-  (unless (bytevector? bv) ($oops who "~s is not a bytevector" bv))
+  (unless (mutable-bytevector? bv) ($oops who "~s is not a mutable bytevector" bv))
   (unless (and (fixnum? n) (not ($fxu< (bytevector-length bv) n)))
     ($oops who "invalid new length ~s for ~s" n bv))
   (bytevector-truncate! bv n))
 
 (define-who (string-truncate! st n)
-  (unless (string? st) ($oops who "~s is not a string" st))
+  (unless (mutable-string? st) ($oops who "~s is not a mutable string" st))
   (unless (and (fixnum? n) (not ($fxu< (string-length st) n)))
     ($oops who "invalid new length ~s for ~s" n st))
   (string-truncate! st n))
@@ -269,33 +269,31 @@
 (define-who make-string
   (case-lambda
     [(n c)
-    ; if this fails, we have to change the test and message below
-     (meta-assert (= (constant maximum-string-length) (constant most-positive-fixnum)))
-     (unless (and (fixnum? n) (fx>= n 0))
-       ($oops who "~s is not a nonnegative fixnum" n))
+     (meta-assert (<= (constant maximum-string-length) (constant most-positive-fixnum)))
+     (unless (and (fixnum? n) ($fxu< n (fx+ (constant maximum-string-length) 1)))
+       ($oops who "~s is not a valid string length" n))
      (unless (char? c)
        ($oops who "~s is not a character" c))
      (make-string n c)]
     [(n)
-    ; if this fails, we have to change the test and message below
-     (meta-assert (= (constant maximum-string-length) (constant most-positive-fixnum)))
-     (unless (and (fixnum? n) (fx>= n 0))
-       ($oops who "~s is not a nonnegative fixnum" n))
+     (meta-assert (<= (constant maximum-string-length) (constant most-positive-fixnum)))
+     (unless (and (fixnum? n) ($fxu< n (fx+ (constant maximum-string-length) 1)))
+       ($oops who "~s is not a valid string length" n))
+     (unless (fx<= n (constant maximum-string-length))
+       ($oops who "~s is too large" n))
      (make-string n)]))
 
-(define make-vector
+(define-who make-vector
    (case-lambda
       [(n x)
-       ; if this fails, we have to change the test and message below
-       (meta-assert (= (constant maximum-vector-length) (constant most-positive-fixnum)))
-       (unless (and (fixnum? n) (fx>= n 0))
-          ($oops 'make-vector "~s is not a nonnegative fixnum" n))
+       (meta-assert (<= (constant maximum-vector-length) (constant most-positive-fixnum)))
+       (unless (and (fixnum? n) ($fxu< n (fx+ (constant maximum-vector-length) 1)))
+         ($oops who "~s is not a valid vector length" n))
        (make-vector n x)]
       [(n)
-       ; if this fails, we have to change the test and message below
-       (meta-assert (= (constant maximum-vector-length) (constant most-positive-fixnum)))
-       (unless (and (fixnum? n) (fx>= n 0))
-          ($oops 'make-vector "~s is not a nonnegative fixnum" n))
+       (meta-assert (<= (constant maximum-vector-length) (constant most-positive-fixnum)))
+       (unless (and (fixnum? n) ($fxu< n (fx+ (constant maximum-vector-length) 1)))
+         ($oops who "~s is not a valid vector length" n))
        (make-vector n)]))
 
 (define $make-eqhash-vector
@@ -308,32 +306,32 @@
 (define-who make-fxvector
   (case-lambda
     [(n x)
-    ; if this fails, we have to change the test and message below
-     (meta-assert (= (constant maximum-fxvector-length) (constant most-positive-fixnum)))
-     (unless (and (fixnum? n) (fx>= n 0))
-       ($oops who "~s is not a nonnegative fixnum" n))
+     (meta-assert (<= (constant maximum-fxvector-length) (constant most-positive-fixnum)))
+     (unless (and (fixnum? n) ($fxu< n (fx+ (constant maximum-fxvector-length) 1)))
+       ($oops who "~s is not a valid fxvector length" n))
      (unless (fixnum? x)
        ($oops who "~s is not a fixnum" x))
      (make-fxvector n x)]
     [(n)
-    ; if this fails, we have to change the test and message below
-     (meta-assert (= (constant maximum-fxvector-length) (constant most-positive-fixnum)))
-     (unless (and (fixnum? n) (fx>= n 0))
-       ($oops who "~s is not a nonnegative fixnum" n))
+     (meta-assert (<= (constant maximum-fxvector-length) (constant most-positive-fixnum)))
+     (unless (and (fixnum? n) ($fxu< n (fx+ (constant maximum-fxvector-length) 1)))
+       ($oops who "~s is not a valid fxvector length" n))
+     (unless (fx<= n (constant maximum-fxvector-length))
+       ($oops who "~s is too large" n))
      (make-fxvector n)]))
 
 (define string-fill!
    (lambda (s c)
-      (unless (string? s)
-         ($oops 'string-fill! "~s is not a string" s))
+      (unless (mutable-string? s)
+         ($oops 'string-fill! "~s is not a mutable string" s))
       (unless (char? c)
          ($oops 'string-fill! "~s is not a character" c))
       (string-fill! s c)))
 
 (define fxvector-fill!
    (lambda (v n)
-      (unless (fxvector? v)
-         ($oops 'fxvector-fill! "~s is not an fxvector" v))
+      (unless (mutable-fxvector? v)
+         ($oops 'fxvector-fill! "~s is not a mutable fxvector" v))
       (unless (fixnum? n)
          ($oops 'fxvector-fill! "~s is not a fixnum" n))
       (fxvector-fill! v n)))
@@ -534,10 +532,13 @@
       ($bigpositive? x)))
 
 (define $string-ref-check? (lambda (s i) ($string-ref-check? s i)))
+(define $string-set!-check? (lambda (s i) ($string-set!-check? s i)))
 
 (define $vector-ref-check? (lambda (v i) ($vector-ref-check? v i)))
+(define $vector-set!-check? (lambda (v i) ($vector-set!-check? v i)))
 
 (define $fxvector-ref-check? (lambda (v i) ($fxvector-ref-check? v i)))
+(define $fxvector-set!-check? (lambda (v i) ($fxvector-set!-check? v i)))
 
 (define $ratio-numerator
    (lambda (q)
@@ -1031,6 +1032,20 @@
    (lambda (v i x)
       (#2%string-set! v i x)))
 
+(define-who $string-set-immutable!
+   (lambda (s)
+     (unless (string? s)
+       ($oops who "~s is not a string" s))
+     (#3%$string-set-immutable! s)))
+
+(define-who mutable-string?
+  (lambda (v)
+    (#3%mutable-string? v)))
+
+(define-who immutable-string?
+  (lambda (v)
+    (#3%immutable-string? v)))
+
 (define char->integer
    (lambda (x)
       (#2%char->integer x)))
@@ -1059,6 +1074,20 @@
   (lambda (v i x)
     (#2%vector-set-fixnum! v i x)))
 
+(define-who $vector-set-immutable!
+   (lambda (v)
+     (unless (vector? v)
+       ($oops who "~s is not a vector" v))
+     (#3%$vector-set-immutable! v)))
+
+(define mutable-vector?
+   (lambda (v)
+     (#3%mutable-vector? v)))
+
+(define immutable-vector?
+   (lambda (v)
+     (#3%immutable-vector? v)))
+
 (define fxvector-length
    (lambda (v)
       (#2%fxvector-length v)))
@@ -1071,6 +1100,20 @@
    (lambda (v i x)
       (#2%fxvector-set! v i x)))
 
+(define-who $fxvector-set-immutable!
+   (lambda (s)
+     (unless (fxvector? s)
+       ($oops who "~s is not a fxvector" s))
+     (#3%$fxvector-set-immutable! s)))
+
+(define mutable-fxvector?
+  (lambda (s)
+    (#3%mutable-fxvector? s)))
+
+(define immutable-fxvector?
+  (lambda (s)
+    (#3%immutable-fxvector? s)))
+
 (define cons (lambda (x y) (cons x y)))
 
 (define car
@@ -1091,6 +1134,8 @@
 
 (define box (lambda (x) (box x)))
 
+(define box-immutable (lambda (x) (box-immutable x)))
+
 (define unbox
    (lambda (b)
       (if (box? b)
@@ -1099,9 +1144,17 @@
 
 (define set-box!
    (lambda (b v)
-      (if (box? b)
+      (if (mutable-box? b)
           (set-box! b v)
-          ($oops 'set-box! "~s is not a box" b))))
+          ($oops 'set-box! "~s is not a mutable box" b))))
+
+(define mutable-box?
+  (lambda (b)
+    (#3%mutable-box? b)))
+
+(define immutable-box?
+  (lambda (b) 
+    (#3%immutable-box? b)))
 
 (define pair? (lambda (x) (pair? x)))