From c81eb6ede070691c6c518ed6aa479eca11437f6e Mon Sep 17 00:00:00 2001
From: Matthew Flatt <mflatt@racket-lang.org>
Date: Sun, 23 Mar 2008 13:25:56 +0000
Subject: [PATCH] add in-lines and some doc clarifications

svn: r9072
---
 collects/scheme/private/for.ss                | 17 +++++++++++
 .../scribblings/reference/sequences.scrbl     | 28 +++++++++++++------
 src/mzscheme/src/module.c                     |  7 +++++
 3 files changed, 44 insertions(+), 8 deletions(-)

diff --git a/collects/scheme/private/for.ss b/collects/scheme/private/for.ss
index 807bcd43b3..4a8d8a501c 100644
--- a/collects/scheme/private/for.ss
+++ b/collects/scheme/private/for.ss
@@ -30,6 +30,7 @@
              (rename *in-bytes in-bytes)
              in-input-port-bytes
              in-input-port-chars
+             in-lines
              in-hash-table
              in-hash-table-keys
              in-hash-table-values
@@ -431,6 +432,22 @@
                                      (lambda (x) (not (eof-object? x)))
                                      (lambda (x v) #t)))))
   
+  (define in-lines
+    (case-lambda
+     [() (in-lines (current-input-port))]
+     [(v) (in-lines v 'any)]
+     [(v mode)
+      (unless (input-port? v) (raise-type-error 'in-lines "input-port" v))
+      (unless (memq mode '(linefeed return return-linefeed any any-one))
+        (raise-type-error 'in-lines "'linefeed, 'return, 'return-linefeed, 'any, or 'any-one)" mode))
+      (make-do-sequence (lambda ()
+                          (values (lambda (v) (read-line v mode))
+                                  (lambda (v) v)
+                                  v
+                                  (lambda (v) #t)
+                                  (lambda (x) (not (eof-object? x)))
+                                  (lambda (x v) #t))))]))
+  
   (define (in-hash-table ht)
     (unless (hash-table? ht) (raise-type-error 'in-hash-table "hash-table" ht))
     (make-do-sequence (lambda () (:hash-table-gen ht cons (lambda (p) (values (car p) (cdr p)))))))
diff --git a/collects/scribblings/reference/sequences.scrbl b/collects/scribblings/reference/sequences.scrbl
index a8ec6b2b0c..b6f77e2304 100644
--- a/collects/scribblings/reference/sequences.scrbl
+++ b/collects/scribblings/reference/sequences.scrbl
@@ -89,12 +89,21 @@ Returns a sequence equivalent to @scheme[str].
 Returns a sequence equivalent to @scheme[bstr].
 @speed[in-bytes "byte string"]}
 
-@defproc[(in-input-port-bytes [inp input-port?]) sequence?]{
-Returns a sequence equivalent to @scheme[inp].}
+@defproc[(in-input-port-bytes [in input-port?]) sequence?]{
+Returns a sequence equivalent to @scheme[in].}
 
-@defproc[(in-input-port-chars [inp input-port?]) sequence?]{ Returns a
-sequence whose elements are read as characters form @scheme[inp] (as
-opposed to using @scheme[inp] directly as a sequence to get bytes).}
+@defproc[(in-input-port-chars [in input-port?]) sequence?]{ Returns a
+sequence whose elements are read as characters form @scheme[in] (as
+opposed to using @scheme[in] directly as a sequence to get bytes).}
+
+@defproc[(in-lines [in input-port? (current-input-port)]
+                   [mode (one-of 'linefeed 'return 'return-linefeed 'any 'any-one) 'any])
+         sequence?]{
+
+Returns a sequence whose elements are the result of @scheme[(read-line
+in mode)] until an end-of-line is encountered. Note that the default
+mode is @scheme['any], whereas the default mode of @scheme[read-line]
+is @scheme['linefeed].}
 
 @defproc[(in-hash-table [ht hash-table?]) sequence?]{
 Returns a sequence equivalent to @scheme[ht].}
@@ -153,8 +162,7 @@ The @scheme[thunk] results define the generated elements as follows:
 @itemize{
 
  @item{The first result is a @scheme[_pos->element] procedure that takes
-       the current position and returns the value(s) for the current element.
-       It is called only once per position.}
+       the current position and returns the value(s) for the current element.}
 
  @item{The second result is a @scheme[_next-pos] procedure that takes
        the current position and returns the next position.}
@@ -176,7 +184,11 @@ The @scheme[thunk] results define the generated elements as follows:
 
 }
 
-}
+Each of the procedures listed above is called only once per position.
+Among the last three procedures, as soon as one of the procedures
+returns @scheme[#f], the sequence ends, and none are call
+again. Typically, one of the functions determines the end condition,
+and the other two functions always return @scheme[#t].}
 
 @section{Sequence Generators}
 
diff --git a/src/mzscheme/src/module.c b/src/mzscheme/src/module.c
index ea3afaa593..0604083b89 100644
--- a/src/mzscheme/src/module.c
+++ b/src/mzscheme/src/module.c
@@ -1037,6 +1037,13 @@ static Scheme_Object *_dynamic_require(int argc, Scheme_Object *argv[],
 			 errname,
 			 name, srcm->modname);
     }
+
+    if (!menv || !menv->toplevel) {
+      scheme_raise_exn(MZEXN_FAIL_CONTRACT,
+                       "%s: module initialization failed: %V",
+                       errname,
+                       srcm->modname);
+    }
     
     b = scheme_bucket_from_table(menv->toplevel, (const char *)srcname);