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: Double unquote/unquote-splicing Date: Tue, 05 Nov 2013 14:14:52 -0500 Message-ID: References: <87wqko6z8g.fsf@nbtrap.com> <874n7sf3pi.fsf@nbtrap.com> <87habsdlwo.fsf@nbtrap.com> <87fvrahovc.fsf@nbtrap.com> NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain X-Trace: ger.gmane.org 1383678910 28420 80.91.229.3 (5 Nov 2013 19:15:10 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Tue, 5 Nov 2013 19:15:10 +0000 (UTC) Cc: emacs-devel@gnu.org To: Nathan Trapuzzano Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Tue Nov 05 20:15:12 2013 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 1Vdm5o-0004fd-7D for ged-emacs-devel@m.gmane.org; Tue, 05 Nov 2013 20:15:12 +0100 Original-Received: from localhost ([::1]:58092 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Vdm5n-0007By-Fd for ged-emacs-devel@m.gmane.org; Tue, 05 Nov 2013 14:15:11 -0500 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:33411) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Vdm5d-00077E-BP for emacs-devel@gnu.org; Tue, 05 Nov 2013 14:15:08 -0500 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Vdm5V-0002GD-So for emacs-devel@gnu.org; Tue, 05 Nov 2013 14:15:01 -0500 Original-Received: from ironport2-out.teksavvy.com ([206.248.154.182]:61873) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Vdm5V-0002G7-OD for emacs-devel@gnu.org; Tue, 05 Nov 2013 14:14:53 -0500 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: Av4EABK/CFFFxLzd/2dsb2JhbABEvw4Xc4IeAQEEAVYjBQsLDiYSFBgNJIgeBrEfkA6RCgOIYZwZgV6DFQ X-IPAS-Result: Av4EABK/CFFFxLzd/2dsb2JhbABEvw4Xc4IeAQEEAVYjBQsLDiYSFBgNJIgeBrEfkA6RCgOIYZwZgV6DFQ X-IronPort-AV: E=Sophos;i="4.84,565,1355115600"; d="scan'208";a="37155779" Original-Received: from 69-196-188-221.dsl.teksavvy.com (HELO pastel.home) ([69.196.188.221]) by ironport2-out.teksavvy.com with ESMTP/TLS/ADH-AES256-SHA; 05 Nov 2013 14:14:52 -0500 Original-Received: by pastel.home (Postfix, from userid 20848) id A1A1C60109; Tue, 5 Nov 2013 14:14:52 -0500 (EST) In-Reply-To: <87fvrahovc.fsf@nbtrap.com> (Nathan Trapuzzano's message of "Tue, 05 Nov 2013 10:03:51 -0500") User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3.50 (gnu/linux) X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 206.248.154.182 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:164975 Archived-At: > I don't think the special syntax does make that clear. You can't use that special syntax for multi-arg unquote and unquote/unquote-splicing. So the special syntax makes it clear that those are expected to take a single arg. And indeed, so far, they can only take a single arg. >> Your example was the first concrete example I've seen where such >> a ,,@foo construct was used and as you've seen it's trivially replaced >> by ,@(list ,@foo) (which is true because ,foo is equivalent to ,@(list >> foo). > Hmm, I'm actually not sure that will always work. Goes to show again that it's too complex for our own good. >> So ,,@ is not a very compelling use. Maybe ,@,@ would be more >> compelling, but I haven't seen any concrete use for it yet, so I can't >> comment. > Can't say I know of a good use of ,@,@. That said, I think it would be > silly for this proposal to stand or fall on that basis. There's a straightforward rewriting of ",,@", and there's no known use case for ",@,@" (which AFAIK can be rewritten ",@(append ,@" anyway if you really need it). It probably doesn't break any code, but I prefer to keep the rule that unquote/unquote-splicing takes a single argument, since that's true 99.99% of the time, so while people are likely to understand the single-arg case, and they're unlikely to understand the multi-arg case. Stefan