From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Drew Adams Newsgroups: gmane.emacs.help Subject: RE: Always using let* Date: Sun, 14 Sep 2014 16:06:17 -0700 (PDT) Message-ID: References: <87fvfukmso.fsf@Equus.decebal.nl> NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: quoted-printable X-Trace: ger.gmane.org 1410736018 30343 80.91.229.3 (14 Sep 2014 23:06:58 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sun, 14 Sep 2014 23:06:58 +0000 (UTC) To: Stefan Monnier , help-gnu-emacs@gnu.org Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Mon Sep 15 01:06:51 2014 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 1XTIsc-0006pt-RA for geh-help-gnu-emacs@m.gmane.org; Mon, 15 Sep 2014 01:06:50 +0200 Original-Received: from localhost ([::1]:56445 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XTIsc-0005QZ-34 for geh-help-gnu-emacs@m.gmane.org; Sun, 14 Sep 2014 19:06:50 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:44038) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XTIsL-0005Q9-4r for help-gnu-emacs@gnu.org; Sun, 14 Sep 2014 19:06:40 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XTIsC-0008Dt-Db for help-gnu-emacs@gnu.org; Sun, 14 Sep 2014 19:06:33 -0400 Original-Received: from aserp1040.oracle.com ([141.146.126.69]:51057) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XTIsC-0008Dp-7K for help-gnu-emacs@gnu.org; Sun, 14 Sep 2014 19:06:24 -0400 Original-Received: from ucsinet22.oracle.com (ucsinet22.oracle.com [156.151.31.94]) by aserp1040.oracle.com (Sentrion-MTA-4.3.2/Sentrion-MTA-4.3.2) with ESMTP id s8EN6LE4007268 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Sun, 14 Sep 2014 23:06:22 GMT Original-Received: from aserz7022.oracle.com (aserz7022.oracle.com [141.146.126.231]) by ucsinet22.oracle.com (8.14.5+Sun/8.14.5) with ESMTP id s8EN6JpD006955 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Sun, 14 Sep 2014 23:06:21 GMT Original-Received: from abhmp0001.oracle.com (abhmp0001.oracle.com [141.146.116.7]) by aserz7022.oracle.com (8.14.4+Sun/8.14.4) with ESMTP id s8EN6J7m008977; Sun, 14 Sep 2014 23:06:19 GMT In-Reply-To: X-Priority: 3 X-Mailer: Oracle Beehive Extensions for Outlook 2.0.1.8.2 (807160) [OL 12.0.6691.5000 (x86)] X-Source-IP: ucsinet22.oracle.com [156.151.31.94] X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.4.x-2.6.x [generic] X-Received-From: 141.146.126.69 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:99892 Archived-At: > > (The other reason is that for some Lisps the bindings of `let' > > can be done in parallel, which can be quicker.) ^^^ ^^^ >=20 > Urban legend! Perhaps you would prefer "could" to "can"? Lisps such as Common Lisp were specifically designed with this parallel evaluation in mind. The spec (and CLTL(2)) specifically emphasizes the inherent parallelism (independence) here that implies the *possibility* of parallel evaluation. Whether a given Common Lisp implementation takes advantage of this inherent parallelism is optional. Likewise for the other explicitly parallel constructs in CL. For `psetf', for example, CLTL says that "the assignments of new values are done in parallel. More precisely, all subforms that are to be evaluated are evaluated from left to right; after all evaluations have been performed, all of the assignments are performed in an unpredictable order."