From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Andy Wingo Newsgroups: gmane.lisp.guile.devel Subject: Re: Equality predicates, signed zeroes, R5RS and R6RS Date: Wed, 02 Feb 2011 21:09:10 +0100 Message-ID: References: <20110131185050.9C10F98298@pluto.mumble.net> <87k4hkyhmu.fsf@yeeloong.netris.org> NNTP-Posting-Host: lo.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Trace: dough.gmane.org 1296677091 20496 80.91.229.12 (2 Feb 2011 20:04:51 GMT) X-Complaints-To: usenet@dough.gmane.org NNTP-Posting-Date: Wed, 2 Feb 2011 20:04:51 +0000 (UTC) Cc: Taylor R Campbell , guile-devel@gnu.org To: Mark H Weaver Original-X-From: guile-devel-bounces+guile-devel=m.gmane.org@gnu.org Wed Feb 02 21:04:47 2011 Return-path: Envelope-to: guile-devel@m.gmane.org Original-Received: from lists.gnu.org ([199.232.76.165]) by lo.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1PkiwX-0002e1-9F for guile-devel@m.gmane.org; Wed, 02 Feb 2011 21:04:45 +0100 Original-Received: from localhost ([127.0.0.1]:39389 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1PkiwW-0004Op-Kn for guile-devel@m.gmane.org; Wed, 02 Feb 2011 15:04:44 -0500 Original-Received: from [140.186.70.92] (port=40620 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1PkiwM-0004MW-2U for guile-devel@gnu.org; Wed, 02 Feb 2011 15:04:36 -0500 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1PkiwK-0002Qv-F4 for guile-devel@gnu.org; Wed, 02 Feb 2011 15:04:33 -0500 Original-Received: from a-pb-sasl-sd.pobox.com ([64.74.157.62]:39901 helo=sasl.smtp.pobox.com) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1PkiwK-0002LI-Cj for guile-devel@gnu.org; Wed, 02 Feb 2011 15:04:32 -0500 Original-Received: from sasl.smtp.pobox.com (unknown [127.0.0.1]) by a-pb-sasl-sd.pobox.com (Postfix) with ESMTP id 8D27D33EC; Wed, 2 Feb 2011 15:05:05 -0500 (EST) DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=pobox.com; h=from:to:cc :subject:references:date:in-reply-to:message-id:mime-version :content-type; s=sasl; bh=J+CEsWBkMlIP1dfi+3NQgKSbBKY=; b=vMO3EB S40RdlpOp70ykigmZEhzD47DtZu37X9CjlkgMAwgiKc4Ry+TgdrHsMR0t7NP35uU V+WpFMLYBqJyGqilxia3WDAFCpqdqg4NSMCQhNRDvid4UHI4lLDjRuNmvtXWNh+F 9mrna8RrzjQURirmkD6MBDBsRZBWo39t/L0WM= DomainKey-Signature: a=rsa-sha1; c=nofws; d=pobox.com; h=from:to:cc :subject:references:date:in-reply-to:message-id:mime-version :content-type; q=dns; s=sasl; b=bxM9oCyLHKNUGjlYwNjH4CpFyzPnKs0K 1qFK55JVDp0+Xbnp78EIiegD8HK9LMZxtjuA+LmG6sM9a18zAmZkVe2RdUvoQVx2 XkRDdj1jOWa9QCsy2UmtaY7zUk0r6O5tSMgCX1azT6NHcTSjv7c5FA+P2VNYhOrS N36vTq5dDTI= Original-Received: from a-pb-sasl-sd.pobox.com (unknown [127.0.0.1]) by a-pb-sasl-sd.pobox.com (Postfix) with ESMTP id 6B24333E2; Wed, 2 Feb 2011 15:05:03 -0500 (EST) Original-Received: from unquote.localdomain (unknown [90.164.198.39]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by a-pb-sasl-sd.pobox.com (Postfix) with ESMTPSA id 83BAF33DC; Wed, 2 Feb 2011 15:05:00 -0500 (EST) In-Reply-To: <87k4hkyhmu.fsf@yeeloong.netris.org> (Mark H. Weaver's message of "Mon, 31 Jan 2011 14:53:29 -0500") User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.2 (gnu/linux) X-Pobox-Relay-ID: B8DEAA32-2F07-11E0-B030-F13235C70CBC-02397024!a-pb-sasl-sd.pobox.com X-detected-operating-system: by eggs.gnu.org: Solaris 10 (beta) X-Received-From: 64.74.157.62 X-BeenThere: guile-devel@gnu.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: "Developers list for Guile, the GNU extensibility library" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Original-Sender: guile-devel-bounces+guile-devel=m.gmane.org@gnu.org Errors-To: guile-devel-bounces+guile-devel=m.gmane.org@gnu.org Xref: news.gmane.org gmane.lisp.guile.devel:11515 Archived-At: On Mon 31 Jan 2011 20:53, Mark H Weaver writes: > Given that everyone agrees that `eqv?' must distinguish 0 from 0.0, it > is already not useful as a numerical `='. Any program that uses it this > way is asking for trouble. Therefore, I don't have qualms about keeping > our existing behavior, namely that (eqv? 0.0 -0.0) returns #f. > > What do you think? This sounds OK to me. I don't have a horse in the race, but the argument that (eqv? 0 0.0) => #f is convincing, especially given the 0.0-or-0 games that many procedures are allowed to play. Andy -- http://wingolog.org/