From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED!not-for-mail From: Paul Eggert Newsgroups: gmane.emacs.devel Subject: Re: Using the GNU GMP Library for Bignums in Emacs Date: Tue, 24 Apr 2018 18:19:29 -0700 Organization: UCLA Computer Science Department Message-ID: References: <29f933ac-a6bf-8742-66a7-0a9d6d3e5a88@disroot.org> <83bmecy6fx.fsf@gnu.org> <0d3175d8-d996-651e-b221-71978bde3a65@cs.ucla.edu> <42cbc5ab-2f02-4aa5-4b19-7b2357f91692@cs.ucla.edu> <1f58acbf-a7d8-bf4e-3d0e-a285515a22e6@cs.ucla.edu> NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-Trace: blaine.gmane.org 1524619063 24530 195.159.176.226 (25 Apr 2018 01:17:43 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Wed, 25 Apr 2018 01:17:43 +0000 (UTC) User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 Cc: eller.helmut@gmail.com, emacs-devel@gnu.org To: rms@gnu.org Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Wed Apr 25 03:17:39 2018 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1fB93x-0006I4-S7 for ged-emacs-devel@m.gmane.org; Wed, 25 Apr 2018 03:17:37 +0200 Original-Received: from localhost ([::1]:33284 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fB964-0002G1-KA for ged-emacs-devel@m.gmane.org; Tue, 24 Apr 2018 21:19:48 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:54080) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fB95t-0002Ej-Cm for emacs-devel@gnu.org; Tue, 24 Apr 2018 21:19:38 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fB95o-00033v-F4 for emacs-devel@gnu.org; Tue, 24 Apr 2018 21:19:37 -0400 Original-Received: from zimbra.cs.ucla.edu ([131.179.128.68]:55702) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1fB95o-000333-7m; Tue, 24 Apr 2018 21:19:32 -0400 Original-Received: from localhost (localhost [127.0.0.1]) by zimbra.cs.ucla.edu (Postfix) with ESMTP id 0B79D16008C; Tue, 24 Apr 2018 18:19:31 -0700 (PDT) Original-Received: from zimbra.cs.ucla.edu ([127.0.0.1]) by localhost (zimbra.cs.ucla.edu [127.0.0.1]) (amavisd-new, port 10032) with ESMTP id yLQkF7DxUQyd; Tue, 24 Apr 2018 18:19:30 -0700 (PDT) Original-Received: from localhost (localhost [127.0.0.1]) by zimbra.cs.ucla.edu (Postfix) with ESMTP id 2F67E16009B; Tue, 24 Apr 2018 18:19:30 -0700 (PDT) X-Virus-Scanned: amavisd-new at zimbra.cs.ucla.edu Original-Received: from zimbra.cs.ucla.edu ([127.0.0.1]) by localhost (zimbra.cs.ucla.edu [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id F5pjaGv1IIRB; Tue, 24 Apr 2018 18:19:30 -0700 (PDT) Original-Received: from Penguin.CS.UCLA.EDU (Penguin.CS.UCLA.EDU [131.179.64.200]) by zimbra.cs.ucla.edu (Postfix) with ESMTPSA id 13F0C16008C; Tue, 24 Apr 2018 18:19:30 -0700 (PDT) In-Reply-To: Content-Language: en-US X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x [fuzzy] X-Received-From: 131.179.128.68 X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.21 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" Xref: news.gmane.org gmane.emacs.devel:224853 Archived-At: On 04/24/2018 06:05 PM, Richard Stallman wrote: > > In such applications, it's routine to have hexadecimal numbers that are wider > > than 32- or 64-bit words. > > What is the motive for using hexadecimal in a case like that? It varies. One motivation is a desire to communicate a number via text more-efficiently than base 10 would provide. > > Even in the standard C library (which lacks bignums), the %x printf format is > > supposed to be used only with unsigned integers. > > I think that's a misleading statement of what it does in C. The rule > is to use it with an unsigned _type_. The type, not the value, is > supposed to be unsigned. In C, if the type is unsigned then the corresponding value is nonnegative. That is, in C there is no such thing as a negative value with an unsigned type. The %x format is supposed to be used only with unsigned types, i.e., only with nonnegative values. > I contend that we want the same behavior in Emacs Lisp, too. I certainly wouldn't want the behavior you suggest. Among other things, Emacs Lisp does not have unsigned types, and I'd rather not introduce such a concept into the language as it'd be needless complexity and an unnecessary divergence from other Lisps. > In Emacs, 0xffffffff will be a bignum. Whether 0xffffffff is a bignum will depend on the platform. On my 64-bit Emacs, 0xffffffff already is supported as a fixnum, and that wouldn't change if bignums were introduced to Emacs. > Is it a bignum in those other systems? It depends on the system, I expect (just as it would in Emacs).