From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Stefan Monnier Newsgroups: gmane.emacs.devel Subject: Re: why does `variable-at-point' return 0? Date: Fri, 20 Apr 2012 22:24:13 -0400 Message-ID: References: <2F0E226322EE44669007194BC8389F81@us.oracle.com> <717003EF5A184D8A91EF489C3A79EB92@us.oracle.com> <87sjfyl18t.fsf@gmail.com> NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain X-Trace: dough.gmane.org 1334975066 11603 80.91.229.3 (21 Apr 2012 02:24:26 GMT) X-Complaints-To: usenet@dough.gmane.org NNTP-Posting-Date: Sat, 21 Apr 2012 02:24:26 +0000 (UTC) Cc: Drew Adams , emacs-devel@gnu.org To: =?utf-8?B?xaB0xJtww6FuIE7Em21lYw==?= Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Sat Apr 21 04:24:25 2012 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1SLPzs-0004fb-0N for ged-emacs-devel@m.gmane.org; Sat, 21 Apr 2012 04:24:24 +0200 Original-Received: from localhost ([::1]:42929 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SLPzr-00048L-5M for ged-emacs-devel@m.gmane.org; Fri, 20 Apr 2012 22:24:23 -0400 Original-Received: from eggs.gnu.org ([208.118.235.92]:57540) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SLPzo-00047t-DF for emacs-devel@gnu.org; Fri, 20 Apr 2012 22:24:21 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1SLPzm-0000PG-PM for emacs-devel@gnu.org; Fri, 20 Apr 2012 22:24:19 -0400 Original-Received: from ironport-out.teksavvy.com ([206.248.143.162]:47975) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SLPzm-0000PC-Kg for emacs-devel@gnu.org; Fri, 20 Apr 2012 22:24:18 -0400 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: ApYIACxOgk/O+K5t/2dsb2JhbABDuCMDgQyBCIIJAQEEAVYjBQsLNBIUGA0kiBwFtjKLYYR5BKRFgV2DAw X-IronPort-AV: E=Sophos;i="4.75,391,1330923600"; d="scan'208";a="175683402" Original-Received: from 206-248-174-109.dsl.teksavvy.com (HELO pastel.home) ([206.248.174.109]) by ironport2-out.teksavvy.com with ESMTP/TLS/ADH-AES256-SHA; 20 Apr 2012 22:24:16 -0400 Original-Received: by pastel.home (Postfix, from userid 20848) id E08A258E55; Fri, 20 Apr 2012 22:24:13 -0400 (EDT) In-Reply-To: <87sjfyl18t.fsf@gmail.com> (=?utf-8?B?IsWgdMSbcMOhbiBOxJtt?= =?utf-8?B?ZWMiJ3M=?= message of "Fri, 20 Apr 2012 20:14:10 +0200") User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.0.94 (gnu/linux) X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 206.248.143.162 X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Original-Sender: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.devel:149886 Archived-At: >>>> All I can think of is that for some reason someone wanted to >>>> test using `symbolp' instead of testing using `not' (or `and'). >>>> But I cannot imagine why. >> That's most likely the reason, so as not to get tripped up by a variable >> whose name happens to be "nil" (unlikely in Lisp, admittedly). > AFAIK, in "nil-lisps" like Elisp or Common Lisp that is not unlikely, > but impossible. In the context of the discussion, the difference between "unlikely" and "impossible" is irrelevant. > Could you explain what you had in mind? I work in formal methods, and from that point of view, "impossible" would basically mean you have a proof that it can't happen, yet in languages like Lisp "can't happen" is pretty much ... "unlikely"? Stefan