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From: iam@Gang-of-Four.Stanford.EDU (Ian Mason)
Newsgroups: comp.lang.lisp
Subject: Re: Adding items to the end of a list.
Message-ID: <1990Sep5.175308.20173@Neon.Stanford.EDU>
Date: 5 Sep 90 17:53:08 GMT
References: <1990Sep5.011910.1177@mentor.com>
Sender: news@Neon.Stanford.EDU (USENET News System)
Reply-To: iam@Gang-of-Four.Stanford.EDU (Ian Mason)
Organization: Stanford University
Lines: 21

i am not sure i understand the point of the posting. 
it is just as easy to write a tail recursive version
of copy-list that conses onto the front, and the
trick of course generalizes to  the usual list
recursion. since i am not fluent in scheme here it is
in vanila lisp

(defun copylist (l)  
  (if (null l) 
      l 
      (let ((w (cons (car l) (cdr l))))(loop (cdr l) w w))))

(defun loop (x y z) 
   (if (null x) z (let ((w (cons (car x) (cdr x))))
                    (progn (rplacd y w)(loop (cdr x) w z)))))

a correctness proof can be found in "science of computer
programming 10 1988 177-210"


		-iam-