From ... Path: archiver1.google.com!news1.google.com!newsfeed.stanford.edu!news.tele.dk!small.news.tele.dk!129.240.148.23!uio.no!nntp.uio.no!ifi.uio.no!not-for-mail From: Erik Naggum Newsgroups: comp.lang.lisp Subject: Re: Totaly newbie trying to learn LISP at uni Date: 10 Oct 2002 22:14:09 +0000 Organization: Naggum Software, Oslo, Norway Lines: 19 Message-ID: <3243276849563719@naggum.no> References: Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit X-Trace: maud.ifi.uio.no 1034288050 18135 129.240.65.5 (10 Oct 2002 22:14:10 GMT) X-Complaints-To: abuse@ifi.uio.no NNTP-Posting-Date: 10 Oct 2002 22:14:10 GMT Mail-Copies-To: never User-Agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.2 Xref: archiver1.google.com comp.lang.lisp:43659 * arien | So how do you rearrange the code so that you instead do a test for y is | not true? A test whether y is not true is a test whether not-y is true. We use (not y) to produce not-y. When you get more experienced with Common Lisp, you may find that you need a short-hand for this if you do it a lot. If you have a Unicode or even a ISO 8859-1 system, you can write the support code to get ¬y to produce (not y) the same way 'y produces (quote y) in the standard syntax because this is such a frequent thing to want, just like #'foo produces (function foo) which you also need quite frequently in Common Lisp. -- Erik Naggum, Oslo, Norway Act from reason, and failure makes you rethink and study harder. Act from faith, and failure makes you blame someone and push harder.