From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: David Kastrup Newsgroups: gmane.emacs.devel Subject: Re: Unary / Date: Thu, 15 Oct 2015 16:02:06 +0200 Message-ID: <871tcww7q9.fsf@fencepost.gnu.org> References: <87pp0gweri.fsf@fencepost.gnu.org> <22047.37539.943171.429065@turnbull.sk.tsukuba.ac.jp> <877fmouyt3.fsf@gnu.org> <87d1wgwclb.fsf@fencepost.gnu.org> NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain X-Trace: ger.gmane.org 1444917838 7688 80.91.229.3 (15 Oct 2015 14:03:58 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Thu, 15 Oct 2015 14:03:58 +0000 (UTC) Cc: "Stephen J. Turnbull" , emacs-devel@gnu.org To: Stefan Monnier Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Thu Oct 15 16:03:57 2015 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 1Zmj8P-0007Zy-6l for ged-emacs-devel@m.gmane.org; Thu, 15 Oct 2015 16:03:57 +0200 Original-Received: from localhost ([::1]:47644 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Zmj8J-0002E4-6I for ged-emacs-devel@m.gmane.org; Thu, 15 Oct 2015 10:03:51 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:50966) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Zmj6j-00029G-Da for emacs-devel@gnu.org; Thu, 15 Oct 2015 10:02:19 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Zmj6d-0003lm-Ny for emacs-devel@gnu.org; Thu, 15 Oct 2015 10:02:13 -0400 Original-Received: from fencepost.gnu.org ([2001:4830:134:3::e]:49909) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Zmj6d-0003lg-Ks; Thu, 15 Oct 2015 10:02:07 -0400 Original-Received: from localhost ([127.0.0.1]:35495 helo=lola) by fencepost.gnu.org with esmtp (Exim 4.82) (envelope-from ) id 1Zmj6d-0001zK-3F; Thu, 15 Oct 2015 10:02:07 -0400 Original-Received: by lola (Postfix, from userid 1000) id 63AFBDF4F5; Thu, 15 Oct 2015 16:02:06 +0200 (CEST) In-Reply-To: (Stefan Monnier's message of "Thu, 15 Oct 2015 09:31:02 -0400") User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/25.0.50 (gnu/linux) X-detected-operating-system: by eggs.gnu.org: Error: Malformed IPv6 address (bad octet value). X-Received-From: 2001:4830:134:3::e 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:191642 Archived-At: Stefan Monnier writes: >> Ah, so there will not be a lot of legacy code relying on the current >> semantics. This would be > [...] >> Since there are about a dozen apparently unrelated changes, the question >> is whether anything specifically relied on this change. > > I don't remember the specific case that motivated the change. > IIRC I changed it mostly because the limitation was arbitrary (as you > can see in the patch, which doesn't actually change the code). > > I didn't know that CL had decided to give a completely different meaning > to the unary / than the natural generalization of the behavior of (/ X1 > X2 ... Xn). It seems backward to me, so I guess my sense of aesthetics > would incite me to simply revert my patch, adding a comment that for the > semantics of the unary / there is a conflict between the natural choice > and CL compatibility. Should we do that for unary - as well? It's exactly the same situation. (- 3) is not the same as (- 3 0) but as (- 0 3), just like (/ 3.0) is not the same as (/ 3.0 1.0) but as (/ 1.0 3.0). That is, given only a single argument, you get the inverse element for addition/multiplication, respectively. -- David Kastrup