From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED!not-for-mail From: Stefan Monnier Newsgroups: gmane.emacs.devel Subject: Re: Why is there no `until' in elisp? Date: Tue, 16 Oct 2018 17:28:28 -0400 Message-ID: References: <87murdu6to.fsf@portable.galex-713.eu> NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: text/plain X-Trace: blaine.gmane.org 1539725474 7491 195.159.176.226 (16 Oct 2018 21:31:14 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Tue, 16 Oct 2018 21:31:14 +0000 (UTC) User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.0.50 (gnu/linux) To: emacs-devel@gnu.org Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Tue Oct 16 23:31:10 2018 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1gCWvk-0001rK-5p for ged-emacs-devel@m.gmane.org; Tue, 16 Oct 2018 23:31:08 +0200 Original-Received: from localhost ([::1]:60292 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gCWxq-0008J2-N5 for ged-emacs-devel@m.gmane.org; Tue, 16 Oct 2018 17:33:18 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:40439) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gCWxA-0008Iq-OM for emacs-devel@gnu.org; Tue, 16 Oct 2018 17:32:37 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gCWx4-0002EW-ST for emacs-devel@gnu.org; Tue, 16 Oct 2018 17:32:36 -0400 Original-Received: from [195.159.176.226] (port=48322 helo=blaine.gmane.org) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1gCWwt-00027F-K8 for emacs-devel@gnu.org; Tue, 16 Oct 2018 17:32:22 -0400 Original-Received: from list by blaine.gmane.org with local (Exim 4.84_2) (envelope-from ) id 1gCWuh-0000Yn-4A for emacs-devel@gnu.org; Tue, 16 Oct 2018 23:30:03 +0200 X-Injected-Via-Gmane: http://gmane.org/ Original-Lines: 18 Original-X-Complaints-To: usenet@blaine.gmane.org Cancel-Lock: sha1:4IL8N+pk/iillXYtAANFKOpuYPo= X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 195.159.176.226 X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.21 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.org@gnu.org Original-Sender: "Emacs-devel" Xref: news.gmane.org gmane.emacs.devel:230428 Archived-At: > [0] such as: (defmacro until (test &rest body) (declare (indent 1)) > `(while (not ,test) ,@body)) I like `until`. As a matter of fact, I think `until` is more important than `while` for the following reason: it should not behave like the one you have above but rather like: (defmacro until (test &rest body) (let (res) (while (not (setq res ,test)) ,@body) res)) While `while` doesn't have much else to return than nil, `until` does have a useful value to return, which is the non-nil value that caused it to exit. Stefan