From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Stefan Monnier Newsgroups: gmane.emacs.devel Subject: Re: Negative nth index Date: Wed, 25 Dec 2024 12:22:00 -0500 Message-ID: References: <865xnc6u9n.fsf@gnu.org> <87jzbs9jlk.fsf@gnu.org> <87r05wahsi.fsf@protonmail.com> Mime-Version: 1.0 Content-Type: text/plain Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="30899"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Gnus/5.13 (Gnus v5.13) Cc: Stefan Kangas , Tassilo Horn , Eli Zaretskii , Anand Tamariya , emacs-devel@gnu.org To: Pip Cet Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Wed Dec 25 18:22:48 2024 Return-path: Envelope-to: ged-emacs-devel@m.gmane-mx.org Original-Received: from lists.gnu.org ([209.51.188.17]) by ciao.gmane.io with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1tQV5r-0007uI-Gk for ged-emacs-devel@m.gmane-mx.org; Wed, 25 Dec 2024 18:22:47 +0100 Original-Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1tQV5H-00080L-PQ; Wed, 25 Dec 2024 12:22:11 -0500 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1tQV5G-00080B-4I for emacs-devel@gnu.org; Wed, 25 Dec 2024 12:22:10 -0500 Original-Received: from mailscanner.iro.umontreal.ca ([132.204.25.50]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1tQV5E-0001tx-HP; Wed, 25 Dec 2024 12:22:09 -0500 Original-Received: from pmg2.iro.umontreal.ca (localhost.localdomain [127.0.0.1]) by pmg2.iro.umontreal.ca (Proxmox) with ESMTP id 319D280456; Wed, 25 Dec 2024 12:22:06 -0500 (EST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=iro.umontreal.ca; s=mail; t=1735147321; bh=TiU/Rt4MLn/OGRx6OcO45TJFIvVmAat6/rX7vtpHi5A=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=dtIQoxM2G1C6AiStcdnlTMghIa4qUkvFWhNfg0ACdSmJ+KHLCn2f7Mt8AgaCY1T/u As+0G86JsIbt3sV2lFCH/qssNk05rBOGavWggUWqLcau6ZJIcoDBA0pz1poTmYPu26 c1EVvaueml2onLJfE7tX7Tn/zPJF+mlCZVtzqKEP6BapJqaIaMBt2hRA+k0vzWAh1u YGjpA33DksigVOguN6aMK/VWUUEoMwT5Dm5Wi0TOLg2w/bo8QMCc1gnfAg5p5Aa+iA GfqaoTR9JhOLKrE4NEo6RcIqWXWKroJFEotiWX/vkMK4eBNM2z0OkdrBt4Mt3+KJdr 9N2u4r8K0yu8g== Original-Received: from mail01.iro.umontreal.ca (unknown [172.31.2.1]) by pmg2.iro.umontreal.ca (Proxmox) with ESMTP id 349D38025B; Wed, 25 Dec 2024 12:22:01 -0500 (EST) Original-Received: from pastel (104-195-225-43.cpe.teksavvy.com [104.195.225.43]) by mail01.iro.umontreal.ca (Postfix) with ESMTPSA id E301F120409; Wed, 25 Dec 2024 12:22:00 -0500 (EST) In-Reply-To: <87r05wahsi.fsf@protonmail.com> (Pip Cet's message of "Tue, 24 Dec 2024 21:33:17 +0000") Received-SPF: pass client-ip=132.204.25.50; envelope-from=monnier@iro.umontreal.ca; helo=mailscanner.iro.umontreal.ca X-Spam_score_int: -42 X-Spam_score: -4.3 X-Spam_bar: ---- X-Spam_report: (-4.3 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, RCVD_IN_DNSWL_MED=-2.3, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.29 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-mx.org@gnu.org Original-Sender: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Xref: news.gmane.io gmane.emacs.devel:327112 Archived-At: >> [ I'd make it return 2 otherwise you can't use it to return the >> last element. ] > I think the OP meant that (nth -1 '(1 2)) is 1 on current Emacs, which > is definitely unexpected. Ah.. you're right that makes a lot more sense. >> I don't see a strong argument in favor of making it index from the end >> rather than signal an error. What would the implementation look like? > I agree, but the current implementation does not signal an error. It > should, and I think that's what the suggestion was. Sorry for misreading. I'd prefer that we signal an error, yes. Not sure it's worth the risk of breaking existing code, OTOH. Stefan