Implement GUARANTEE-STREAM-PAIR.

diff --git a/v7/src/runtime/runtime.pkg b/v7/src/runtime/runtime.pkg
index f12501888c7e49ad694b6c6871de00fa29adbfab..53d1873ad1f336a6bc65a6898d12b658cf57fbed 100644 (file)
--- a/v7/src/runtime/runtime.pkg
+++ b/v7/src/runtime/runtime.pkg
@@ -1,6 +1,6 @@
 #| -*-Scheme-*-
 
-$Id: runtime.pkg,v 14.529 2005/01/23 17:53:16 cph Exp $
+$Id: runtime.pkg,v 14.530 2005/02/08 00:10:55 cph Exp $
 
 Copyright 1988,1989,1990,1991,1992,1993 Massachusetts Institute of Technology
 Copyright 1994,1995,1996,1997,1998,1999 Massachusetts Institute of Technology
@@ -3821,6 +3821,8 @@ USA.
   (export ()
          condition-type:illegal-stream-element
          empty-stream?
+         error:not-stream-pair
+         guarantee-stream-pair
          head
          list->stream
          make-prime-numbers-stream

diff --git a/v7/src/runtime/stream.scm b/v7/src/runtime/stream.scm
index 440339ddc3078abd0c84b055a95b24ac5e081c37..b9b7061939d6b816842b927f5e3b37ef4a2d6b88 100644 (file)
--- a/v7/src/runtime/stream.scm
+++ b/v7/src/runtime/stream.scm
@@ -1,9 +1,9 @@
 #| -*-Scheme-*-
 
-$Id: stream.scm,v 14.19 2004/06/12 02:15:48 cph Exp $
+$Id: stream.scm,v 14.20 2005/02/08 00:11:11 cph Exp $
 
 Copyright 1986,1987,1988,1989,1992,1995 Massachusetts Institute of Technology
-Copyright 1998,2003,2004 Massachusetts Institute of Technology
+Copyright 1998,2003,2004,2005 Massachusetts Institute of Technology
 
 This file is part of MIT/GNU Scheme.
 
@@ -33,14 +33,14 @@ USA.
   (and (pair? stream)
        (promise? (cdr stream))))
 
+(define-guarantee stream-pair "stream pair")
+
 (define (stream-car stream)
-  (if (not (stream-pair? stream))
-      (error:wrong-type-argument stream "stream" 'STREAM-CAR))
+  (guarantee-stream-pair stream 'STREAM-CAR)
   (car stream))
 
 (define (stream-cdr stream)
-  (if (not (stream-pair? stream))
-      (error:wrong-type-argument stream "stream" 'STREAM-CDR))
+  (guarantee-stream-pair stream 'STREAM-CDR)
   (force (cdr stream)))
 
 (define the-empty-stream '())
@@ -247,7 +247,7 @@ USA.
       (cons-stream (car list) (list->stream (cdr list)))
       (begin
        (if (not (null? list))
-           (error:wrong-type-argument list "list" 'LIST->STREAM))
+           (error:not-list list 'LIST->STREAM))
        '())))
 
 (define (stream->list stream)