From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED!not-for-mail From: Paul Eggert Newsgroups: gmane.emacs.devel Subject: Re: [PATCH] Add new lisp function length= with bytecode support Date: Mon, 27 Feb 2017 15:06:31 -0800 Organization: UCLA Computer Science Department Message-ID: <3fee7074-67f0-8fba-7fd9-0d600caf5d99@cs.ucla.edu> References: <64Kl8OYdaKer-3Ey7GHVD9He6bX8yYHaS_NjEwp7Wqc4Zb7xu8IQV3ExvjCLKlBWHVVr_HNUhd55i_BVXNHnpxjnXc6hPgWvWkc3bIO8e7s=@protonmail.com> <83k28bpq57.fsf@gnu.org> NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-Trace: blaine.gmane.org 1488238619 4742 195.159.176.226 (27 Feb 2017 23:36:59 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Mon, 27 Feb 2017 23:36:59 +0000 (UTC) User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.7.0 Cc: emacs-devel@gnu.org To: Gdobbins Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Tue Feb 28 00:36:54 2017 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 1ciUqb-0000Zc-En for ged-emacs-devel@m.gmane.org; Tue, 28 Feb 2017 00:36:53 +0100 Original-Received: from localhost ([::1]:57612 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ciUqh-0006LB-8W for ged-emacs-devel@m.gmane.org; Mon, 27 Feb 2017 18:36:59 -0500 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:48639) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ciUNN-0005T6-4L for emacs-devel@gnu.org; Mon, 27 Feb 2017 18:06:42 -0500 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ciUNJ-0008Kg-St for emacs-devel@gnu.org; Mon, 27 Feb 2017 18:06:41 -0500 Original-Received: from zimbra.cs.ucla.edu ([131.179.128.68]:51676) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1ciUNJ-0008Hf-N6 for emacs-devel@gnu.org; Mon, 27 Feb 2017 18:06:37 -0500 Original-Received: from localhost (localhost [127.0.0.1]) by zimbra.cs.ucla.edu (Postfix) with ESMTP id 0334116004F; Mon, 27 Feb 2017 15:06:33 -0800 (PST) Original-Received: from zimbra.cs.ucla.edu ([127.0.0.1]) by localhost (zimbra.cs.ucla.edu [127.0.0.1]) (amavisd-new, port 10032) with ESMTP id t6nM7CF_Op-6; Mon, 27 Feb 2017 15:06:32 -0800 (PST) Original-Received: from localhost (localhost [127.0.0.1]) by zimbra.cs.ucla.edu (Postfix) with ESMTP id 4CF0716006D; Mon, 27 Feb 2017 15:06:32 -0800 (PST) X-Virus-Scanned: amavisd-new at zimbra.cs.ucla.edu Original-Received: from zimbra.cs.ucla.edu ([127.0.0.1]) by localhost (zimbra.cs.ucla.edu [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id YD3sdX4SmF42; Mon, 27 Feb 2017 15:06:32 -0800 (PST) Original-Received: from Penguin.CS.UCLA.EDU (Penguin.CS.UCLA.EDU [131.179.64.200]) by zimbra.cs.ucla.edu (Postfix) with ESMTPSA id 34B0516004F; Mon, 27 Feb 2017 15:06:32 -0800 (PST) In-Reply-To: X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x [fuzzy] X-Received-From: 131.179.128.68 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:212631 Archived-At: On 02/27/2017 10:43 AM, Gdobbins wrote: > I looked in the manual for a place where length= should be documented, > but didn't find one. I thought the docstring was sufficient. Perhaps I > was mistaken. It should be documented in doc/lispref/sequences.texi, no? As the intended use of length= is to compare lengths, it's confusing that it also accepts markers and floats, plus that makes the implementation a bit slower as it can't use EQ to compare lengths. It would be cleaner and simpler for length= to accept only sequences and integers, as Alexandria does. I assume that markers and floats were put in only so that the byte-compiler could optimize expressions like (= (length FOO) BAR) without worrying about incompatibilities in the very-unlikely case where BAR is a float or a marker. In that case, perhaps the the byte-compiler should use a specialized length= function that is not visible to the user, so that the user-visible function (if any) can be kept cleaner.