From: David Vázquez <davazp@gmail.com>
Date: Fri, 8 Feb 2013 22:47:13 +0000 (+0100)
Subject: Iterative MAPCAR
X-Git-Url: http://repo.macrolet.net/gitweb/?a=commitdiff_plain;h=6f98aac6382d655a64592bd32395b55f8854d46c;p=jscl.git

Iterative MAPCAR
---

diff --git a/ecmalisp.lisp b/ecmalisp.lisp
index 9951c03..cdf33d0 100644
--- a/ecmalisp.lisp
+++ b/ecmalisp.lisp
@@ -350,10 +350,14 @@
     (concat-two s1 s2))
 
   (defun mapcar (func list)
-    (if (null list)
-        '()
-        (cons (funcall func (car list))
-              (mapcar func (cdr list)))))
+    (let* ((head (cons 'sentinel nil))
+	   (tail head))
+      (while (not (null list))
+	(let ((new (cons (funcall func (car list)) nil)))
+	  (rplacd tail new)
+	  (setq tail new
+		list (cdr list))))
+      (cdr head)))
 
   (defun identity (x) x)