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: How to avoid compiler warning `unused lexical variable' for `dolist' or `dotimes'? Date: Thu, 07 Jan 2021 23:40:11 -0500 Message-ID: References: <7eec4142-3c37-4084-9ea1-73df5df2c821@default> Mime-Version: 1.0 Content-Type: text/plain Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="18271"; 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: sha1:3ZWwFHrocJ2VaZ8b6mB5dkzqJVM= Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane-mx.org@gnu.org Fri Jan 08 06:01:46 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 1kxjuE-0004ez-0m for geh-help-gnu-emacs@m.gmane-mx.org; Fri, 08 Jan 2021 06:01:46 +0100 Original-Received: from localhost ([::1]:35000 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kxjuD-0003gM-0c for geh-help-gnu-emacs@m.gmane-mx.org; Fri, 08 Jan 2021 00:01:45 -0500 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:54104) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kxjZY-0007F1-03 for help-gnu-emacs@gnu.org; Thu, 07 Jan 2021 23:40:24 -0500 Original-Received: from ciao.gmane.io ([116.202.254.214]:55010) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kxjZV-0001lF-It for help-gnu-emacs@gnu.org; Thu, 07 Jan 2021 23:40:23 -0500 Original-Received: from list by ciao.gmane.io with local (Exim 4.92) (envelope-from ) id 1kxjZT-0003Fh-MU for help-gnu-emacs@gnu.org; Fri, 08 Jan 2021 05:40:19 +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:127088 Archived-At: > FWIW, Common Lisp has several iteration constructs that let you specify an > optional return value up front (as you would say, in a sub-sub-expression). > Not just `dolist' and `dotimes'. `do', for instance. There are a few other such cases, indeed. I think most of them are like `do` in the sense that they're *very* rarely used in ELisp (and correspondingly most ELisp programmers have no idea what it does). FWIW, I remember that I used to like `do*` back when I was programming in Common Lisp, but nowadays I find it rather inscrutable. In that category I think Scheme's named let is infinitely superior: both more general and easier to understand. Too bad that it's kind of a pain to implement efficiently in ELisp, but Vincent's `recur-let` gives a pretty good approximation (still more general and easier to understand than `do*`). (c.f. https://github.com/VincentToups/recur). > There's nothing particularly odd, new, or unlispy about such design. > It's very old in Lisp iteration. Old doesn't mean good. Stefan