add `pseudo-random-generator-vector?'

Also, adjust docs to clarify that `vector->pseudo-random-generator!'
can be used as a more complete seeding function.

collects/scribblings/reference/numbers.scrbl

@@ -796,7 +796,13 @@ Seeds the current pseudo-random number generator with
 @racket[k]. Seeding a generator sets its internal state
 deterministically; that is, seeding a generator with a particular
 number forces it to produce a sequence of pseudo-random numbers that
-is the same across runs and across platforms.}
+is the same across runs and across platforms.
+
+The @racket[random-seed] function is convenient for some purposes, but
+note that the space of states for a pseudo-random number generator is
+much larger that the space of allowed values for @racket[k]. Use
+@racket[vector->pseudo-random-generator!] to set a pseudo-random
+number generator to any of its possible states.}
 
 
 @defproc[(make-pseudo-random-generator) pseudo-random-generator?]{
@@ -818,7 +824,7 @@ used by @racket[random].}
 
 
 @defproc[(pseudo-random-generator->vector [generator pseudo-random-generator?])
-         vector?]{
+         pseudo-random-generator-vector?]{
 
 Produces a vector that represents the complete internal state of
 @racket[generator]. The vector is suitable as an argument to
@@ -826,25 +832,30 @@ Produces a vector that represents the complete internal state of
 its current state (across runs and across platforms).}
 
 
-@defproc[(vector->pseudo-random-generator [vec vector?])
+@defproc[(vector->pseudo-random-generator [vec pseudo-random-generator-vector?])
          pseudo-random-generator?]{
 
 Produces a pseudo-random number generator whose internal state
-corresponds to @racket[vec]. The vector @racket[vec] must contain six
-exact integers; the first three integers must be in the range
-@racket[0] to @racket[4294967086], inclusive; the last three integers
-must be in the range @racket[0] to @racket[4294944442], inclusive; at
-least one of the first three integers must be non-zero; and at least
-one of the last three integers must be non-zero.}
+corresponds to @racket[vec].}
 
 @defproc[(vector->pseudo-random-generator! [generator pseudo-random-generator?]
-                                           [vec vector?])
+                                           [vec pseudo-random-generator-vector?])
          void?]{
 
 Like @racket[vector->pseudo-random-generator], but changes
 @racket[generator] to the given state, instead of creating a new
 generator.}
 
+
+@defproc[(pseudo-random-generator-vector? [v any/c]) boolean?]{
+
+Returns @racket[#t] if @racket[v] is a vector of six exact integers,
+where the first three integers are in the range @racket[0] to
+@racket[4294967086], inclusive; the last three integers are in the
+range @racket[0] to @racket[4294944442], inclusive; at least one of
+the first three integers is non-zero; and at least one of the last
+three integers is non-zero. Otherwise, the result is @racket[#f].}
+
 @; ------------------------------------------------------------------------
 @subsection{Number--String Conversions}
 

collects/tests/racket/number.rktl

@@ -2230,6 +2230,22 @@
 (arity-test current-evt-pseudo-random-generator 0 1)
 (err/rt-test (current-pseudo-random-generator 10))
 
+(let ([g (current-pseudo-random-generator)])
+  (test #t pseudo-random-generator-vector? (pseudo-random-generator->vector g)))
+(test #f pseudo-random-generator-vector? #())
+(test #t pseudo-random-generator-vector? #(1 2 3 4 5 6))
+(test #f pseudo-random-generator-vector? #(0 0 0 4 5 6))
+(test #f pseudo-random-generator-vector? #(1 2 3 0 0 0))
+(test #f pseudo-random-generator-vector? #(1 2 3 4 5 #f))
+(err/rt-test (vector->pseudo-random-generator #()))
+(err/rt-test (vector->pseudo-random-generator #(0 0 0 1 2 3)))
+;; Known state should produce known values:
+(parameterize ([current-pseudo-random-generator
+                (vector->pseudo-random-generator
+                 #(3620087466 1904163406 3177592043 1406334318 257151704 3090455638))])
+  (test 5353 random 10000)
+  (test 8571 random 10000)
+  (test 9729 random 10000))
 
 (test #t = 0 0)
 (test #f = 0 (expt 2 32))

doc/release-notes/racket/HISTORY.txt

@@ -1,3 +1,6 @@
+Version 5.2.0.6
+Added pseudo-random-generator-vector?
+
 Version 5.2.0.5
 Cross-module inlining of trivial functions, plus map, for-each,
  andmap, and ormap; 'compiler-hint:cross-module-inline hint

src/racket/src/numstr.c

@@ -28,7 +28,7 @@
    the error messages are better this way.
 
    Also, for no particularly good reason, random-number support is
-   here, though the real work is in random.inc (from FreeBSD). */
+   here, though the real work is in newrandom.inc. */
 
 #include "schpriv.h"
 #include <math.h>
@@ -53,6 +53,7 @@ static Scheme_Object *pseudo_random_generator_p(int argc, Scheme_Object **argv);
 static Scheme_Object *sch_unpack(int argc, Scheme_Object *argv[]);
 static Scheme_Object *sch_pack(int argc, Scheme_Object *argv[]);
 static Scheme_Object *sch_pack_bang(int argc, Scheme_Object *argv[]);
+static Scheme_Object *sch_check_pack(int argc, Scheme_Object *argv[]);
 
 static char *number_to_allocated_string(int radix, Scheme_Object *obj, int alloc);
 
@@ -151,6 +152,11 @@ void scheme_init_numstr(Scheme_Env *env)
 						      "pseudo-random-generator->vector", 
 						      1, 1), 
 			     env);
+  scheme_add_global_constant("pseudo-random-generator-vector?",
+                             scheme_make_prim_w_arity(sch_check_pack,
+						      "pseudo-random-generator-vector?", 
+						      1, 1), 
+			     env);
   scheme_add_global_constant("pseudo-random-generator?", 
 			     scheme_make_prim_w_arity(pseudo_random_generator_p,
 						      "pseudo-random-generator?", 
@@ -2292,7 +2298,7 @@ sch_random(int argc, Scheme_Object *argv[])
 }
 
 static Scheme_Object *
-do_pack(const char *name, int argc, Scheme_Object *argv[], int set)
+do_pack(const char *name, int argc, Scheme_Object *argv[], int set, int check)
 {
   Scheme_Object *s;
   GC_CAN_IGNORE Scheme_Random_State rs;
@@ -2304,11 +2310,14 @@ do_pack(const char *name, int argc, Scheme_Object *argv[], int set)
     }
   }
 
-  if (SCHEME_VECTORP(argv[set]))
-    s = pack_rand_state(argv[set], (set ? &rs : NULL));
+  if (SCHEME_VECTORP(argv[set]) && (SCHEME_VEC_SIZE(argv[set]) == 6))
+    s = pack_rand_state(argv[set], ((set || check) ? &rs : NULL));
   else
     s = NULL;
 
+  if (check)
+    return (s ? scheme_true : scheme_false);
+
   if (!s)
     scheme_wrong_type(name,
 		      "vector of six elements, three in [0, 4294967086] and three in [0, 4294944442], "
@@ -2333,13 +2342,19 @@ do_pack(const char *name, int argc, Scheme_Object *argv[], int set)
 static Scheme_Object *
 sch_pack(int argc, Scheme_Object *argv[])
 {
-  return do_pack("vector->pseudo-random-generator", argc, argv, 0);
+  return do_pack("vector->pseudo-random-generator", argc, argv, 0, 0);
 }
 
 static Scheme_Object *
 sch_pack_bang(int argc, Scheme_Object *argv[])
 {
-  return do_pack("vector->pseudo-random-generator!", argc, argv, 1);
+  return do_pack("vector->pseudo-random-generator!", argc, argv, 1, 0);
+}
+
+static Scheme_Object *
+sch_check_pack(int argc, Scheme_Object *argv[])
+{
+  return do_pack("pseudo-random-generator-vector?", argc, argv, 0, 1);
 }
 
 static Scheme_Object *

src/racket/src/schminc.h

@@ -13,7 +13,7 @@
 
 #define USE_COMPILED_STARTUP 1
 
-#define EXPECTED_PRIM_COUNT 1041
+#define EXPECTED_PRIM_COUNT 1042
 #define EXPECTED_UNSAFE_COUNT 78
 #define EXPECTED_FLFXNUM_COUNT 68
 #define EXPECTED_FUTURES_COUNT 11

src/racket/src/schvers.h

@@ -13,12 +13,12 @@
    consistently.)
 */
 
-#define MZSCHEME_VERSION "5.2.0.5"
+#define MZSCHEME_VERSION "5.2.0.6"
 
 #define MZSCHEME_VERSION_X 5
 #define MZSCHEME_VERSION_Y 2
 #define MZSCHEME_VERSION_Z 0
-#define MZSCHEME_VERSION_W 5
+#define MZSCHEME_VERSION_W 6
 
 #define MZSCHEME_VERSION_MAJOR ((MZSCHEME_VERSION_X * 100) + MZSCHEME_VERSION_Y)
 #define MZSCHEME_VERSION_MINOR ((MZSCHEME_VERSION_Z * 1000) + MZSCHEME_VERSION_W)