From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Barry Fishman Newsgroups: gmane.emacs.devel Subject: Re: Always-true predicate? Date: Wed, 17 Feb 2021 11:59:25 -0500 Message-ID: <7ny2fmljf6.fsf@ecube.ecubist.org> References: <875z2qoqc6.fsf@gnus.org> <87zh02n9zl.fsf@gnus.org> Mime-Version: 1.0 Content-Type: text/plain Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="8985"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/28.0.50 (gnu/linux) To: emacs-devel@gnu.org Cancel-Lock: sha1:ItMtk3LZD9vcaNMCJratL7hkuyg= Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Wed Feb 17 18:06:31 2021 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 1lCQHV-0002BZ-Tu for ged-emacs-devel@m.gmane-mx.org; Wed, 17 Feb 2021 18:06:29 +0100 Original-Received: from localhost ([::1]:41322 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lCQHU-0005SG-QD for ged-emacs-devel@m.gmane-mx.org; Wed, 17 Feb 2021 12:06:28 -0500 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:37672) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lCQAt-0008Gg-4n for emacs-devel@gnu.org; Wed, 17 Feb 2021 11:59:40 -0500 Original-Received: from ciao.gmane.io ([116.202.254.214]:54268) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lCQAr-0006E3-1w for emacs-devel@gnu.org; Wed, 17 Feb 2021 11:59:38 -0500 Original-Received: from list by ciao.gmane.io with local (Exim 4.92) (envelope-from ) id 1lCQAm-0004S7-Aj for emacs-devel@gnu.org; Wed, 17 Feb 2021 17:59:32 +0100 X-Injected-Via-Gmane: http://gmane.org/ Received-SPF: pass client-ip=116.202.254.214; envelope-from=ged-emacs-devel@m.gmane-mx.org; helo=ciao.gmane.io X-Spam_score_int: -15 X-Spam_score: -1.6 X-Spam_bar: - X-Spam_report: (-1.6 / 5.0 requ) BAYES_00=-1.9, HEADER_FROM_DIFFERENT_DOMAINS=0.25, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.23 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" Xref: news.gmane.io gmane.emacs.devel:265020 Archived-At: On 2021-02-17 13:40:14 +01, Lars Ingebrigtsen wrote: > Andrea Corallo writes: > >> Maybe something like CONSTANTLY would be more generic? >> > I'm not sure that's a net win. The use case here is, for instance > > (defalias 'mouse-sel--ignore #'ignore) > (defvar after-focus-change-function #'ignore > > etc, which is fast and easy to read. If you're doing a predicate, you > now have to say > > (setq some-predicate #'ignore) > > but > > (setq some-predicate (lambda (&rest _) t)) > > or > > (setq some-predicate (constantly t)) > > which seems unsymmetric. Something symmetric would be: (setq some-predicate (constantly nil)) Ignore seems more about its lack of effects rather than its return value. -- Barry Fishman