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.help Subject: Re: FW: How to avoid compiler warning `unused lexical variable' for `dolist' or `dotimes'? Date: Thu, 07 Jan 2021 22:36:20 -0500 Message-ID: References: <87o8i1ou7m.fsf@zoho.eu> <0db0bc9d-7efb-4d3e-8462-545d0a5b25f5@default> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="30575"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/28.0.50 (gnu/linux) To: help-gnu-emacs@gnu.org Cancel-Lock: sha1:W0URQW/whQX26pBH961On0qqf1A= Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane-mx.org@gnu.org Fri Jan 08 04:36:48 2021 Return-path: Envelope-to: geh-help-gnu-emacs@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 1kxia0-0007t1-L4 for geh-help-gnu-emacs@m.gmane-mx.org; Fri, 08 Jan 2021 04:36:48 +0100 Original-Received: from localhost ([::1]:59438 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kxiZz-0006eR-Ly for geh-help-gnu-emacs@m.gmane-mx.org; Thu, 07 Jan 2021 22:36:47 -0500 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:42210) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kxiZh-0006eK-8F for help-gnu-emacs@gnu.org; Thu, 07 Jan 2021 22:36:29 -0500 Original-Received: from ciao.gmane.io ([116.202.254.214]:57794) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kxiZg-0005DK-1C for help-gnu-emacs@gnu.org; Thu, 07 Jan 2021 22:36:29 -0500 Original-Received: from list by ciao.gmane.io with local (Exim 4.92) (envelope-from ) id 1kxiZd-0007Y0-JM for help-gnu-emacs@gnu.org; Fri, 08 Jan 2021 04:36:25 +0100 X-Injected-Via-Gmane: http://gmane.org/ Received-SPF: pass client-ip=116.202.254.214; envelope-from=geh-help-gnu-emacs@m.gmane-mx.org; helo=ciao.gmane.io X-Spam_score_int: -16 X-Spam_score: -1.7 X-Spam_bar: - X-Spam_report: (-1.7 / 5.0 requ) BAYES_00=-1.9, HEADER_FROM_DIFFERENT_DOMAINS=0.248, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: help-gnu-emacs@gnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Users list for the GNU Emacs text editor List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane-mx.org@gnu.org Original-Sender: "help-gnu-emacs" Xref: news.gmane.io gmane.emacs.help:127085 Archived-At: > (times (length list))) > (dotimes (nr times new-list) > (let* ((item (elt list nr))) Please don't do that: such a "dotimes + elt" is fine when iterating over a *vector*, but when iterating over a list it means it'll take time O(nē) since `elt` on a list takes time O(n). So it's *much* better to use `dolist` (or `mapc` or ...) in that case. Stefan