From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Emanuel Berg Newsgroups: gmane.emacs.help Subject: Re: [External] : Re: Testing whether a list contains at least one non-nil element Date: Sat, 29 Oct 2022 11:20:10 +0200 Message-ID: <87r0yr56lx.fsf@dataswamp.org> References: <87r0yw85la.fsf@dataswamp.org> <87lep031vm.fsf@web.de> Mime-Version: 1.0 Content-Type: text/plain Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="25571"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Gnus/5.13 (Gnus v5.13) To: help-gnu-emacs@gnu.org Cancel-Lock: sha1:UsErRcZCI9YSA8yFxIOLbJXG3bk= Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane-mx.org@gnu.org Sat Oct 29 23:29:05 2022 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 1ootO4-0006SP-Bb for geh-help-gnu-emacs@m.gmane-mx.org; Sat, 29 Oct 2022 23:29:04 +0200 Original-Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ootNr-0000aK-KU; Sat, 29 Oct 2022 17:28:51 -0400 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 1ooi5S-0000X9-Sy for help-gnu-emacs@gnu.org; Sat, 29 Oct 2022 05:25:06 -0400 Original-Received: from ciao.gmane.io ([116.202.254.214]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1ooi5R-0003hw-6H for help-gnu-emacs@gnu.org; Sat, 29 Oct 2022 05:25:06 -0400 Original-Received: from list by ciao.gmane.io with local (Exim 4.92) (envelope-from ) id 1ooi5O-0008QA-K1 for help-gnu-emacs@gnu.org; Sat, 29 Oct 2022 11:25:02 +0200 X-Injected-Via-Gmane: http://gmane.org/ Mail-Followup-To: help-gnu-emacs@gnu.org Mail-Copies-To: never 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=0.249, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=no autolearn_force=no X-Spam_action: no action X-Mailman-Approved-At: Sat, 29 Oct 2022 17:28:50 -0400 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: , Original-Sender: "help-gnu-emacs" Errors-To: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane-mx.org@gnu.org Xref: news.gmane.io gmane.emacs.help:140499 Archived-At: Michael Heerdegen wrote: >> If you are doing it "by hand", why not indulge in Lisp's >> "classic elegance", like so: >> >> (defun has-non-nil (lst) >> (cond >> ((null lst) nil) >> ((consp lst) (or (not (null (car lst))) (has-non-nil (cdr lst)))) >> (t (error "Not a proper list! You cheater!")))) > > You don't want to implement such functions in Emacs with > recursion because you'll easily hit `max-lisp-eval-depth' > when they are called. Sorry to tell you, but a loop is the > preferable way in Elisp. He knows that ... > -- underground experts united https://dataswamp.org/~incal