From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Filipp Gunbin Newsgroups: gmane.emacs.help Subject: Re: What does "lacks a prefix" mean? Date: Mon, 13 Jul 2015 15:26:14 +0300 Message-ID: References: <1e0ad02f-ca3e-495c-bb85-61f77090d31d@googlegroups.com> <87bnfmqzn2.fsf@kuiper.lan.informatimago.com> <87io9ui67a.fsf@nl106-137-147.student.uu.se> <871tghj720.fsf@nl106-137-147.student.uu.se> NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain X-Trace: ger.gmane.org 1436790424 12521 80.91.229.3 (13 Jul 2015 12:27:04 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Mon, 13 Jul 2015 12:27:04 +0000 (UTC) Cc: help-gnu-emacs@gnu.org To: Stefan Monnier Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Mon Jul 13 14:26:51 2015 Return-path: Envelope-to: geh-help-gnu-emacs@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1ZEcot-0006vi-8S for geh-help-gnu-emacs@m.gmane.org; Mon, 13 Jul 2015 14:26:51 +0200 Original-Received: from localhost ([::1]:54587 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZEcos-0005Zo-Hr for geh-help-gnu-emacs@m.gmane.org; Mon, 13 Jul 2015 08:26:50 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:45709) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZEcoS-0005Qa-3Z for help-gnu-emacs@gnu.org; Mon, 13 Jul 2015 08:26:28 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZEcoN-0007jF-2Z for help-gnu-emacs@gnu.org; Mon, 13 Jul 2015 08:26:24 -0400 Original-Received: from out2-smtp.messagingengine.com ([66.111.4.26]:54925) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZEcoM-0007iw-NY for help-gnu-emacs@gnu.org; Mon, 13 Jul 2015 08:26:18 -0400 Original-Received: from compute3.internal (compute3.nyi.internal [10.202.2.43]) by mailout.nyi.internal (Postfix) with ESMTP id 2FD6220A61 for ; Mon, 13 Jul 2015 08:26:17 -0400 (EDT) Original-Received: from frontend2 ([10.202.2.161]) by compute3.internal (MEProxy); Mon, 13 Jul 2015 08:26:17 -0400 DKIM-Signature: v=1; a=rsa-sha1; c=relaxed/relaxed; d=fastmail.fm; h=cc :content-type:date:from:in-reply-to:message-id:mime-version :references:subject:to:x-sasl-enc:x-sasl-enc; s=mesmtp; bh=LC9j5 to8a6tPUX9QjoIDdC8bVJY=; b=IQJAmyrpA7b0MTrXlYwsd1f4JLnFdC+XbMA2p tIQEGb5WtOkDtfwdACjgwQYVOC2o1kQb97/MPmR2GXI94AuvhMEOfaKcaYAOS46i ixl0vT1oCHXuUd3bJcX/Y+GHfK3O9/B+mPXEaAiBuxSA8nzVyw0yIQJKPAQd91w4 ubJKOI= DKIM-Signature: v=1; a=rsa-sha1; c=relaxed/relaxed; d= messagingengine.com; h=cc:content-type:date:from:in-reply-to :message-id:mime-version:references:subject:to:x-sasl-enc :x-sasl-enc; s=smtpout; bh=LC9j5to8a6tPUX9QjoIDdC8bVJY=; b=T5Edr K1aHaLyO9BiRILuPPuy8FrlCMgcu8hePCV5x2lnkAufx248taE1xq8boOkm9g9QW ZjwncsIVL+5fnNvEfEInIIBe1+3DoRIS/Z5MKBNqMmll3SuSSBSPgZYSC/ZVgStV KKdMcdtLSuRcrg8McQpMSTvDrVxHBMBVKmRkXw= X-Sasl-enc: zMI/wv+LLHx1ECSkUeHKny4HKaa1ZMn9OdxlaA6E1c7k 1436790376 Original-Received: from fgunbin.local (unknown [94.25.218.10]) by mail.messagingengine.com (Postfix) with ESMTPA id 911EC68012A; Mon, 13 Jul 2015 08:26:16 -0400 (EDT) In-Reply-To: (Stefan Monnier's message of "Fri, 10 Jul 2015 13:04:30 -0400") User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/25.0.50 (darwin) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 66.111.4.26 X-BeenThere: help-gnu-emacs@gnu.org X-Mailman-Version: 2.1.14 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.org@gnu.org Original-Sender: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.help:105679 Archived-At: On 10/07/2015 13:04 -0400, Stefan Monnier wrote: >>> let* says "I need variables which depend on each >>> other" and if they're really not, that look strange. > > If let behaved like let* it wouldn't look strange to you. Many other > functional languages dropped the "simultaneous let" and only kept the > equivalent of let* (or even letrec). But if 90% of users make the distinction and 10% of them don't it would cause confusion. If everybody uses the same construct then it does not matter. letrec is nice :-) >>> And probably it's a bit slower. > > Regarding efficiency, there's no clear winner between the two. > It's basically irrelevant. I meant that there could be an extra inner frame for each of the bindings in let*, while only one in let. I don't have enough knowledge of emacs lisp implementation to say for sure, that's why "probably" in my comment. >>> And non-parallelizable theoretically :) > > In practice neither is easily parallelizable anyway. Is it because each of the value expression could modify something in the environment? > And the work needed to auto-convert a "let*" to a "let" when possible > is trivial in comparison to what's needed to parallelize the code. So > again, it's really irrelevant. Ok, thanks. Filipp