From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Andreas Schwab Newsgroups: gmane.emacs.devel Subject: Re: Unary / Date: Thu, 15 Oct 2015 14:09:52 +0200 Message-ID: References: <87pp0gweri.fsf@fencepost.gnu.org> NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain X-Trace: ger.gmane.org 1444911281 25381 80.91.229.3 (15 Oct 2015 12:14:41 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Thu, 15 Oct 2015 12:14:41 +0000 (UTC) Cc: emacs-devel@gnu.org To: David Kastrup Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Thu Oct 15 14:14:32 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 1ZmhQT-0005Xc-IL for ged-emacs-devel@m.gmane.org; Thu, 15 Oct 2015 14:14:29 +0200 Original-Received: from localhost ([::1]:47185 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZmhQS-00015o-Ob for ged-emacs-devel@m.gmane.org; Thu, 15 Oct 2015 08:14:28 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:43805) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZmhM6-0007wI-8B for emacs-devel@gnu.org; Thu, 15 Oct 2015 08:09:59 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZmhM5-0002JO-9G for emacs-devel@gnu.org; Thu, 15 Oct 2015 08:09:58 -0400 Original-Received: from mx2.suse.de ([195.135.220.15]:36546) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZmhM1-0002EV-Aq; Thu, 15 Oct 2015 08:09:53 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Original-Received: from relay2.suse.de (charybdis-ext.suse.de [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 50C38AC6C; Thu, 15 Oct 2015 12:09:51 +0000 (UTC) X-Yow: When you get your PH.D. will you get able to work at BURGER KING? In-Reply-To: <87pp0gweri.fsf@fencepost.gnu.org> (David Kastrup's message of "Thu, 15 Oct 2015 13:30:09 +0200") User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x (no timestamps) [generic] X-Received-From: 195.135.220.15 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:191633 Archived-At: David Kastrup writes: > I was surprised to discover that unary / does not work analogously to > unary -, namely creating the multiplicative inverse. > > In Elisp, (/ 2.0) returns 2.0. In Common Lisp > > (and in Scheme), this returns 0.5. > > Any reason for that? The Elisp behavior does not appear overly useful. Probably because before Emacs supported floats this wasn't such a useful operation. Andreas. -- Andreas Schwab, SUSE Labs, schwab@suse.de GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE 1748 E4D4 88E3 0EEA B9D7 "And now for something completely different."