From b27143a96c70f3398b4cadc2126ea15e42863bec Mon Sep 17 00:00:00 2001
From: Alex Shinn <ashinn@users.noreply.github.com>
Date: Thu, 26 Sep 2013 16:09:39 +0900
Subject: [PATCH] Fixing list-copy for improper lists.

---
 lib/scheme/extras.scm | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/lib/scheme/extras.scm b/lib/scheme/extras.scm
index 93e6c3c5..05717b4b 100644
--- a/lib/scheme/extras.scm
+++ b/lib/scheme/extras.scm
@@ -150,7 +150,10 @@
       (if (>= i n) res (lp (+ i 1) (cons init res))))))
 
 (define (list-copy ls)
-  (reverse (reverse ls)))
+  (let lp ((ls ls) (res '()))
+    (if (pair? ls)
+        (lp (cdr ls) (cons (car ls) res))
+        (append (reverse res) ls))))
 
 (define (list-set! ls k x)
   (cond ((null? ls) (error "invalid list index"))