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: Nil as a case key Date: 05 Oct 2002 13:23:30 +0000 Organization: Naggum Software, Oslo, Norway Lines: 25 Message-ID: <3242813010210309@naggum.no> References: <1e249696.0210050246.5cc94526@posting.google.com> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit X-Trace: maud.ifi.uio.no 1033824210 17215 129.240.65.5 (5 Oct 2002 13:23:30 GMT) X-Complaints-To: abuse@ifi.uio.no NNTP-Posting-Date: 5 Oct 2002 13:23:30 GMT Mail-Copies-To: never User-Agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.2 Xref: archiver1.google.com comp.lang.lisp:43110 * Rand Sobriquet | "If there is only one key for a clause, then that key may be written | in place of a list of that key, provided that no ambiguity results. | Such a ``singleton key'' may not be nil (which is confusable with (), | a list of no keys), t, otherwise, or a cons." While it says that `nil´ is not allowed as a singleton key, it is clearly allowed as a list of no keys, since that it explicitly mentioned. | So, do you think it is correct to say that use of nil alone as a key is | not allowed? In ACL it's use is ignored, and in Lispworks it's use leads | to a warning about undefined behavior. LispWorks is wrong on this one. If you are a supported customer, complain and you will most probably receive a patch forthwith. Case keys with `()´ are important because it is often much, much easier to machine-generate (as in macros) an empty list of keys than to make the whole clause go away. -- 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.