From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Eric Abrahamsen Newsgroups: gmane.emacs.help Subject: Re: (unless ...) vs (when (not ...)) Date: Fri, 16 Jul 2021 16:12:19 -0700 Message-ID: <87mtqlua3w.fsf@ericabrahamsen.net> References: Mime-Version: 1.0 Content-Type: text/plain Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="23771"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/28.0.50 (gnu/linux) Cc: help-gnu-emacs To: Hongyi Zhao Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane-mx.org@gnu.org Sat Jul 17 01:12:47 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 1m4X0h-00061z-AY for geh-help-gnu-emacs@m.gmane-mx.org; Sat, 17 Jul 2021 01:12:47 +0200 Original-Received: from localhost ([::1]:49568 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1m4X0g-0007wM-BV for geh-help-gnu-emacs@m.gmane-mx.org; Fri, 16 Jul 2021 19:12:46 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:58232) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1m4X0L-0007wE-2k for help-gnu-emacs@gnu.org; Fri, 16 Jul 2021 19:12:25 -0400 Original-Received: from mail.ericabrahamsen.net ([52.70.2.18]:56816) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1m4X0J-00020g-9Q for help-gnu-emacs@gnu.org; Fri, 16 Jul 2021 19:12:24 -0400 Original-Received: from localhost (c-71-197-184-122.hsd1.wa.comcast.net [71.197.184.122]) (Authenticated sender: eric@ericabrahamsen.net) by mail.ericabrahamsen.net (Postfix) with ESMTPSA id BB674FEB2F; Fri, 16 Jul 2021 23:12:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ericabrahamsen.net; s=mail; t=1626477141; bh=IrlE3paMhSinIZ2O2WwbJxDOhHUvTKIUVA5PFnimKUA=; h=From:To:Cc:Subject:References:Date:In-Reply-To:From; b=vPRCdXoEszS7Ed5ULesVHOX2LH0TK0X9p+eABm8582iGCrpEu8I+WvWRgEg/jU1Wi /D1LbSVP/GW/y1Zds2efduKePOrYTIYVZFyyFZuCUUB4KbFpxnhk+1pLSWLYPPJC9V kXI47aR56hK2M3/3aoYYyTjdCtRV/Qnxf7rHF+LY= In-Reply-To: (Hongyi Zhao's message of "Sat, 17 Jul 2021 06:42:40 +0800") Received-SPF: pass client-ip=52.70.2.18; envelope-from=eric@ericabrahamsen.net; helo=mail.ericabrahamsen.net X-Spam_score_int: -43 X-Spam_score: -4.4 X-Spam_bar: ---- X-Spam_report: (-4.4 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_MED=-2.3, SPF_HELO_NONE=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: 2.1.23 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:131776 Archived-At: Hongyi Zhao writes: > Should I use (unless ...) or (when (not ...))? Which one is preferable? In terms of compilation, they both turn into `if' statements, so there's no real difference there. Personally I find that, when I'm "reading" the code out loud in my head, one approach will sound more natural than the other, which can make things a little quicker to parse mentally. But it really depends on what the condition is and how it's tested.