From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED!not-for-mail From: Stefan Monnier Newsgroups: gmane.emacs.devel Subject: Re: Making 'eq' == 'eql' in bignum branch Date: Mon, 20 Aug 2018 11:20:45 -0400 Message-ID: References: <29f933ac-a6bf-8742-66a7-0a9d6d3e5a88@disroot.org> <87tvpdnzgy.fsf@tromey.com> <4c2a814f-c254-29e5-39cf-11b5f2e5c9c8@cs.ucla.edu> <49d8ba62-c9a5-9203-d882-8e900b441ff3@cs.ucla.edu> <8e0320d9-e0d0-2b57-57cc-2df4399f133c@cs.ucla.edu> <87lgaio7xd.fsf@tromey.com> <877em1cb0i.fsf@tromey.com> <765767b2-d2e5-a9a6-f724-d58ecf4847bb@cs.ucla.edu> <76081b5d-8c10-0a37-2c97-d4864c0faa80@cs.ucla.edu> <09153aed-361d-4f82-d9ac-b502314769ae@cs.ucla.edu> <583514c3-956c-80c3-12b2-69e67bfe2bde@cs.ucla.edu> NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: text/plain X-Trace: blaine.gmane.org 1534778395 14757 195.159.176.226 (20 Aug 2018 15:19:55 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Mon, 20 Aug 2018 15:19:55 +0000 (UTC) User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.0.50 (gnu/linux) To: emacs-devel@gnu.org Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Mon Aug 20 17:19:51 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 1frly9-0003f9-4l for ged-emacs-devel@m.gmane.org; Mon, 20 Aug 2018 17:19:49 +0200 Original-Received: from localhost ([::1]:47697 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1frm0D-0007cm-PT for ged-emacs-devel@m.gmane.org; Mon, 20 Aug 2018 11:21:57 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:42273) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1frlzF-0007cW-Gm for emacs-devel@gnu.org; Mon, 20 Aug 2018 11:20:58 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1frlzC-0004aN-Rh for emacs-devel@gnu.org; Mon, 20 Aug 2018 11:20:57 -0400 Original-Received: from [195.159.176.226] (port=43106 helo=blaine.gmane.org) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1frlzC-0004Ye-KL for emacs-devel@gnu.org; Mon, 20 Aug 2018 11:20:54 -0400 Original-Received: from list by blaine.gmane.org with local (Exim 4.84_2) (envelope-from ) id 1frlx3-0002B8-Si for emacs-devel@gnu.org; Mon, 20 Aug 2018 17:18:41 +0200 X-Injected-Via-Gmane: http://gmane.org/ Original-Lines: 14 Original-X-Complaints-To: usenet@blaine.gmane.org Cancel-Lock: sha1:48JH8tz90i9WG2KJq+hqr6Lkw2M= X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 195.159.176.226 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:228731 Archived-At: >> the time to lookup up a GMP number in a hash table basically should >> never be longer than the time it took to construct this number in the >> first place > Doesn't a similar argument apply to the cost of construcing an Lisp float > (including memory allocation)? If we hashed floats as well as bignums, > eq==eql would be trivial. Float operations are fundamentally much faster than a hash-lookup. The fact that we heap-allocate them makes the relative cost of hash-consing lower, but I think it's still likely to increase run-time by a factor higher than 2x. Stefan