From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Stefan Monnier Newsgroups: gmane.emacs.devel Subject: Re: Understanding macroexp.el Date: Wed, 18 Nov 2015 08:36:52 -0500 Message-ID: References: <87h9kjd2dl.fsf@web.de> <87d1v7cy4w.fsf@web.de> NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain X-Trace: ger.gmane.org 1447853848 25422 80.91.229.3 (18 Nov 2015 13:37:28 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Wed, 18 Nov 2015 13:37:28 +0000 (UTC) Cc: Andreas Schwab , Emacs Development To: Michael Heerdegen Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Wed Nov 18 14:37:18 2015 Return-path: Envelope-to: ged-emacs-devel@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 1Zz2vE-0007PZ-6Z for ged-emacs-devel@m.gmane.org; Wed, 18 Nov 2015 14:37:16 +0100 Original-Received: from localhost ([::1]:36001 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Zz2vD-0001ky-DU for ged-emacs-devel@m.gmane.org; Wed, 18 Nov 2015 08:37:15 -0500 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:52526) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Zz2uw-0001jL-1f for emacs-devel@gnu.org; Wed, 18 Nov 2015 08:36:58 -0500 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Zz2us-0002RO-Qh for emacs-devel@gnu.org; Wed, 18 Nov 2015 08:36:57 -0500 Original-Received: from pruche.dit.umontreal.ca ([132.204.246.22]:40995) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Zz2us-0002RC-Lm for emacs-devel@gnu.org; Wed, 18 Nov 2015 08:36:54 -0500 Original-Received: from fmsmemgm.homelinux.net (lechon.iro.umontreal.ca [132.204.27.242]) by pruche.dit.umontreal.ca (8.14.1/8.14.1) with ESMTP id tAIDaqUg029541; Wed, 18 Nov 2015 08:36:52 -0500 Original-Received: by fmsmemgm.homelinux.net (Postfix, from userid 20848) id 27101AE25F; Wed, 18 Nov 2015 08:36:52 -0500 (EST) In-Reply-To: <87d1v7cy4w.fsf@web.de> (Michael Heerdegen's message of "Wed, 18 Nov 2015 13:03:59 +0100") User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/25.1.50 (gnu/linux) X-NAI-Spam-Flag: NO X-NAI-Spam-Threshold: 5 X-NAI-Spam-Score: 0 X-NAI-Spam-Rules: 1 Rules triggered RV5494=0 X-NAI-Spam-Version: 2.3.0.9418 : core <5494> : inlines <4008> : streams <1540125> : uri <2085164> X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 132.204.246.22 X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.14 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-bounces+ged-emacs-devel=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.devel:194709 Archived-At: >> For byte-compiled code there should be no difference between the two >> expansions. > What's the use of `macroexp-unprogn' then at all? It's when you care to generate slightly cleaner code it's easy to do so. It usually doesn't really matter much. > Or does it make a difference in other cases? I can't remember exactly what motivated me to introduce macroexp-unprogn, but I don't think it was a strong need. I can retroactively come up with scenarios where it could make a difference, but they all seem reasonably infrequent. E.g. (+ 1 2) will be optimized to 3, but (+ 1 (progn 2)) won't. Stefan