From: Joe Marshall <eval.apply@gmail.com>
Date: Mon, 13 Jun 2011 14:58:29 +0000 (-0700)
Subject: Define list-set\!
X-Git-Tag: release-9.1.0~22^2~9
X-Git-Url: https://birchwood-abbey.net/git?a=commitdiff_plain;h=03d478b854981003ea9d88a01e2c2ce7d7bf937e;p=mit-scheme.git

Define list-set\!
---

diff --git a/src/runtime/list.scm b/src/runtime/list.scm
index fa861904a..25751542a 100644
--- a/src/runtime/list.scm
+++ b/src/runtime/list.scm
@@ -326,6 +326,12 @@ USA.
 	(error:bad-range-argument index 'LIST-REF))
     (car tail)))
 
+(define (list-set! list index new-value)
+  (let ((tail (list-tail list index)))
+    (if (not (pair? tail))
+	(error:bad-range-argument index 'LIST-SET!))
+    (set-car! tail new-value)))
+
 (define (list-tail list index)
   (guarantee-index-fixnum index 'LIST-TAIL)
   (let loop ((list list) (index* index))