Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sdd.hp.com!wuarchive!psuvax1!psuvm!cunyvm!jefhc
From: JEFHC@CUNYVM
Newsgroups: comp.lang.lisp
Subject: novice question
Message-ID: <90285.160549JEFHC@CUNYVM.BITNET>
Date: 12 Oct 90 20:05:49 GMT
Organization: City University of New York/ University Computer Center
Lines: 20

I realize that this is a very elementary question, but after
banging my head against the wall for several days I still
can't find an answer.

I am trying to write a procedure that will produce the
mirror image of a list,
      (mirror '((a b)(c(d e))))  gives ((( e d)c)(a b)
                 but
(defun mirror (l)
   (cond((null l)nil)
        ((atom l)l)
        (cons (mirror(rest l))(mirror(first l))))))
                      yields
((NIL (NIL (NIL . E) .D) . C (NIL . B) .A)

I've tried every condition under the sun, and have managed to
get rid of the .'s (by changin (atom l)(list l)  ), but
not the NILS.

Thanks for your help.     .... Julie