From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: David Kastrup Newsgroups: gmane.lisp.guile.devel Subject: Re: Bug in documentation for eq? ? Date: Wed, 20 Jun 2012 13:47:45 +0200 Organization: Organization?!? Message-ID: <87mx3yb3xa.fsf@fencepost.gnu.org> References: <87vcimb70s.fsf@fencepost.gnu.org> <87oboe2qti.fsf@pobox.com> <87r4tab4m6.fsf@fencepost.gnu.org> NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain X-Trace: dough.gmane.org 1340192900 2551 80.91.229.3 (20 Jun 2012 11:48:20 GMT) X-Complaints-To: usenet@dough.gmane.org NNTP-Posting-Date: Wed, 20 Jun 2012 11:48:20 +0000 (UTC) To: guile-devel@gnu.org Original-X-From: guile-devel-bounces+guile-devel=m.gmane.org@gnu.org Wed Jun 20 13:48:20 2012 Return-path: Envelope-to: guile-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 1ShJOT-00044Q-6A for guile-devel@m.gmane.org; Wed, 20 Jun 2012 13:48:17 +0200 Original-Received: from localhost ([::1]:33667 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ShJOT-0004sB-6m for guile-devel@m.gmane.org; Wed, 20 Jun 2012 07:48:17 -0400 Original-Received: from eggs.gnu.org ([208.118.235.92]:59028) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ShJOP-0004s1-OQ for guile-devel@gnu.org; Wed, 20 Jun 2012 07:48:15 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ShJOJ-0005e2-B0 for guile-devel@gnu.org; Wed, 20 Jun 2012 07:48:13 -0400 Original-Received: from plane.gmane.org ([80.91.229.3]:58685) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ShJOJ-0005dg-4d for guile-devel@gnu.org; Wed, 20 Jun 2012 07:48:07 -0400 Original-Received: from list by plane.gmane.org with local (Exim 4.69) (envelope-from ) id 1ShJOE-0003cV-3W for guile-devel@gnu.org; Wed, 20 Jun 2012 13:48:02 +0200 Original-Received: from p508eb018.dip.t-dialin.net ([80.142.176.24]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Wed, 20 Jun 2012 13:48:02 +0200 Original-Received: from dak by p508eb018.dip.t-dialin.net with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Wed, 20 Jun 2012 13:48:02 +0200 X-Injected-Via-Gmane: http://gmane.org/ Original-Lines: 25 Original-X-Complaints-To: usenet@dough.gmane.org X-Gmane-NNTP-Posting-Host: p508eb018.dip.t-dialin.net X-Face: 2FEFf>]>q>2iw=B6, xrUubRI>pR&Ml9=ao@P@i)L:\urd*t9M~y1^:+Y]'C0~{mAl`oQuAl \!3KEIp?*w`|bL5qr,H)LFO6Q=qx~iH4DN; i"; /yuIsqbLLCh/!U#X[S~(5eZ41to5f%E@'ELIi$t^ Vc\LWP@J5p^rst0+('>Er0=^1{]M9!p?&:\z]|;&=NP3AhB!B_bi^]Pfkw User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.1.50 (gnu/linux) Cancel-Lock: sha1:DuPpAkcPVMY/KE6lsLVIRWPsA8A= X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 80.91.229.3 X-BeenThere: guile-devel@gnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: "Developers list for Guile, the GNU extensibility library" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: guile-devel-bounces+guile-devel=m.gmane.org@gnu.org Original-Sender: guile-devel-bounces+guile-devel=m.gmane.org@gnu.org Xref: news.gmane.org gmane.lisp.guile.devel:14643 Archived-At: David Kastrup writes: > I think it is completely absurd. It would mean, for example, that > (memq x (list x)) > is generally unspecified. It would mean that things like > (eq? (car x) (car x)) > are generally unspecified even when x is a pair. So that we can have (eq? x x) but not (eq? (car x) (car x)). I really don't care what the standard claims. That a Scheme object should be able to become un-eq? to itself just because it is a number is nonsense. That different number expressions might or might not end up as one object because of a lack of identity is fine. But that a Scheme object might split into several un-eq? identities is schizophrenic. That would violate more invariants than anything. It is fine if the optimizer decides not tracking the identity of numbers. But that means that, absent any reliable identity information, it must declare equal numbers as eq?, not as un-eq?. This is a one-way street. Other options don't make sense. -- David Kastrup