From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Stefan Monnier Newsgroups: gmane.emacs.devel Subject: Re: lists, plain conses and length Date: Thu, 03 Sep 2020 22:26:51 -0400 Message-ID: References: <20200904022334.791EBC2177B@raman-glaptop.localdomain> Mime-Version: 1.0 Content-Type: text/plain Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="28619"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/28.0.50 (gnu/linux) Cc: emacs-devel@gnu.org To: "T.V Raman" Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Fri Sep 04 04:27:29 2020 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 1kE1Ro-0007N7-VC for ged-emacs-devel@m.gmane-mx.org; Fri, 04 Sep 2020 04:27:28 +0200 Original-Received: from localhost ([::1]:37224 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kE1Ro-0003Go-2B for ged-emacs-devel@m.gmane-mx.org; Thu, 03 Sep 2020 22:27:28 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:41408) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kE1RJ-0002j7-22 for emacs-devel@gnu.org; Thu, 03 Sep 2020 22:26:57 -0400 Original-Received: from mailscanner.iro.umontreal.ca ([132.204.25.50]:41797) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kE1RH-0004xs-4l for emacs-devel@gnu.org; Thu, 03 Sep 2020 22:26:56 -0400 Original-Received: from pmg2.iro.umontreal.ca (localhost.localdomain [127.0.0.1]) by pmg2.iro.umontreal.ca (Proxmox) with ESMTP id 5B65F80D0E; Thu, 3 Sep 2020 22:26:54 -0400 (EDT) Original-Received: from mail01.iro.umontreal.ca (unknown [172.31.2.1]) by pmg2.iro.umontreal.ca (Proxmox) with ESMTP id 98ADD806F7; Thu, 3 Sep 2020 22:26:52 -0400 (EDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=iro.umontreal.ca; s=mail; t=1599186412; bh=S10lFM6WICJUBcDtSKHpPKlHwbjitRYlsU1Ajrro7So=; h=From:To:Cc:Subject:References:Date:In-Reply-To:From; b=POSqNH+OviJCLMVXDvDlK8TBmE7i1qegj/HssSLuo/LJY1egjWZslbNtQO/K7Ein5 jbNsIyhoQY/wKidCW8E0sJiyzGDdQKB/C+h3cNQHqNgnRuiM5v5Cj9Jvsq5wGl/HwG Vxjj34+dV+c9Gwh/rtKBtvRZSqGlK9B9JuqJ9MO17ndNr6jmSyfqSddnakf6ZBdin1 HUhFFpD+aKlwJM1BFvUK2Bk+xvU2hTMW7ioOAkH+QU8VIsoGq6bHrfxRcOrEfbM8Og HtTfe22nAOSvGsPccnXyN3oJa3p6G/5Yk05oRy+oeDzWY7iHZ9/RAlikcRRymQGFkr 9Zu3lAd8xuZyQ== Original-Received: from alfajor (unknown [45.72.232.131]) by mail01.iro.umontreal.ca (Postfix) with ESMTPSA id 6EF8512078A; Thu, 3 Sep 2020 22:26:52 -0400 (EDT) In-Reply-To: <20200904022334.791EBC2177B@raman-glaptop.localdomain> (T. V. Raman's message of "Thu, 3 Sep 2020 19:23:34 -0700 (PDT)") Received-SPF: pass client-ip=132.204.25.50; envelope-from=monnier@iro.umontreal.ca; helo=mailscanner.iro.umontreal.ca X-detected-operating-system: by eggs.gnu.org: First seen = 2020/09/03 21:08:49 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] X-Spam_score_int: -42 X-Spam_score: -4.3 X-Spam_bar: ---- X-Spam_report: (-4.3 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-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: 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:254512 Archived-At: > Q: how does one distinguish a cons from a list. A: check `null` (tongue in cheek) Stefan PS: Hint: `(listp X)` is the same as `(or (consp X) (null X))`