From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Tomas Hlavaty Newsgroups: gmane.emacs.help Subject: Re: Advantage using mapc over dolist Date: Mon, 02 Dec 2024 22:07:08 +0100 Message-ID: <878qsxlrpf.fsf@neko.mail-host-address-is-not-set> References: <87ed2qpo3o.fsf@gnu.org> <871pyqfl62.fsf@web.de> <87r06por3q.fsf@neko.mail-host-address-is-not-set> Mime-Version: 1.0 Content-Type: text/plain Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="18076"; mail-complaints-to="usenet@ciao.gmane.io" Cc: Michael Heerdegen , help-gnu-emacs@gnu.org To: Heime Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane-mx.org@gnu.org Mon Dec 02 22:07:48 2024 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 1tIDdz-0004XU-TE for geh-help-gnu-emacs@m.gmane-mx.org; Mon, 02 Dec 2024 22:07:47 +0100 Original-Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1tIDdW-0004CY-BQ; Mon, 02 Dec 2024 16:07:19 -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 1tIDdT-0004CI-3S for help-gnu-emacs@gnu.org; Mon, 02 Dec 2024 16:07:15 -0500 Original-Received: from logand.com ([37.48.87.44]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1tIDdQ-00057B-2x for help-gnu-emacs@gnu.org; Mon, 02 Dec 2024 16:07:13 -0500 Original-Received: by logand.com (Postfix, from userid 1001) id AB32E1A0369; Mon, 2 Dec 2024 22:07:09 +0100 (CET) X-Mailer: emacs 29.4 (via feedmail 11-beta-1 I) In-Reply-To: Received-SPF: pass client-ip=37.48.87.44; envelope-from=tom@logand.com; helo=logand.com X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: help-gnu-emacs@gnu.org X-Mailman-Version: 2.1.29 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-bounces+geh-help-gnu-emacs=m.gmane-mx.org@gnu.org Xref: news.gmane.io gmane.emacs.help:148508 Archived-At: On Mon 02 Dec 2024 at 20:17, Heime wrote: > How can I find an example of exiting prematurely from mapc? silly example: (catch 'done (let ((z 0)) (mapc (lambda (x) (if (< x 10) (setq z (+ z x)) (throw 'done z))) '(3 5 7 13)))) You can search emacs sources for mapc. I have a custom rg-emacs function for that: (rg-emacs "mapc ") which finds tempo-is-user-element function showing something interesting: (defun tempo-is-user-element (element) "Try all the user-defined element handlers in `tempo-user-elements'." ;; Sigh... I need (some list) (catch 'found (mapc (lambda (handler) (let ((result (funcall handler element))) (if result (throw 'found result)))) tempo-user-elements) (throw 'found nil))) although in Common Lisp, I would avoid catch, throw and mapc and used dolist with return or return-from instead: (defun tempo-is-user-element (element) (dolist (handler tempo-user-elements) (let ((z (funcall handler element))) (when z (cl-return z))))) This is more readable than the catch, mapc, throw code in Emacs. Unfortunately, cl-return-from does not seems to be as convenient. cl-return might do what I expect cl:return to be doing.