From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Eric Abrahamsen Newsgroups: gmane.emacs.help Subject: Re: Quick pcase question Date: Thu, 03 Mar 2016 09:13:45 +0800 Message-ID: <87io144b3q.fsf@ericabrahamsen.net> References: <87lh615gt8.fsf@ericabrahamsen.net> <87mvqhw3a4.fsf@web.de> <87ziuh3z6p.fsf@ericabrahamsen.net> <87h9gpw1mx.fsf@web.de> <87vb553xfp.fsf@ericabrahamsen.net> <87bn6xvzdj.fsf@web.de> <874mcovlkl.fsf@russet.org.uk> NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain X-Trace: ger.gmane.org 1456967661 32658 80.91.229.3 (3 Mar 2016 01:14:21 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Thu, 3 Mar 2016 01:14:21 +0000 (UTC) To: help-gnu-emacs@gnu.org Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Thu Mar 03 02:14:11 2016 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 1abHqF-0003h7-3Y for geh-help-gnu-emacs@m.gmane.org; Thu, 03 Mar 2016 02:14:11 +0100 Original-Received: from localhost ([::1]:59924 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1abHqE-0007Gg-8e for geh-help-gnu-emacs@m.gmane.org; Wed, 02 Mar 2016 20:14:10 -0500 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:37560) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1abHq3-0007GD-Ka for help-gnu-emacs@gnu.org; Wed, 02 Mar 2016 20:14:00 -0500 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1abHq0-0002yG-EN for help-gnu-emacs@gnu.org; Wed, 02 Mar 2016 20:13:59 -0500 Original-Received: from plane.gmane.org ([80.91.229.3]:42570) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1abHq0-0002yB-7X for help-gnu-emacs@gnu.org; Wed, 02 Mar 2016 20:13:56 -0500 Original-Received: from list by plane.gmane.org with local (Exim 4.69) (envelope-from ) id 1abHpw-0003UX-5j for help-gnu-emacs@gnu.org; Thu, 03 Mar 2016 02:13:52 +0100 Original-Received: from 123.123.22.37 ([123.123.22.37]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Thu, 03 Mar 2016 02:13:52 +0100 Original-Received: from eric by 123.123.22.37 with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Thu, 03 Mar 2016 02:13:52 +0100 X-Injected-Via-Gmane: http://gmane.org/ Original-Lines: 35 Original-X-Complaints-To: usenet@ger.gmane.org X-Gmane-NNTP-Posting-Host: 123.123.22.37 User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/25.1.50 (gnu/linux) Cancel-Lock: sha1:AFwIo62TdYi4VfPPcxLP9d8N8p4= X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 80.91.229.3 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:109407 Archived-At: phillip.lord@russet.org.uk (Phillip Lord) writes: > Michael Heerdegen writes: > >> Eric Abrahamsen writes: >> >>> But the fact is that pcase is (very complex and very useful) syntax >>> sugar. I just wrote a pcase clause that looks like: >>> >>> `((,(and f-string (pred stringp)) . ,(and class (pred symbolp))) >>> . ,(and regexp (pred stringp))) >>> >>> And that's kind of awful. The whole point of pcase should be concision, >>> but that looks pretty terrible. >> >> :-P >> >> Maybe separate the testing and the binding operations, like: > > What about this? > > (pcase tst > ((and > `(symbolla . ,x) > (guard (stringp x))) > (message "cdr is a string: %s" x))) That seems quite a bit better -- I really haven't yet wrapped my head around the possible permutations of upatterns and qpatterns. Still a bit ungainly when you have multiple clauses, but it does look a little more intuitive. Thanks to you both! E