From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED!not-for-mail From: Andy Moreton Newsgroups: gmane.emacs.devel Subject: Re: Replace trivial pcase occurrences in the Emacs sources Date: Wed, 31 Oct 2018 00:08:27 +0000 Message-ID: <867ehzx9j8.fsf@gmail.com> References: <86mur137n8.fsf@gmail.com> <20181029130132.GB4195@ACM> <20181029134722.GC4195@ACM> <83r2g8klf9.fsf@gnu.org> <9bfd9d19-3b6b-57cd-50a0-24660707768b@gmail.com> <20181030181434.GB5705@ACM> <87231bd6-d4a3-e117-06b9-774ec482d62f@gmail.com> NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Trace: blaine.gmane.org 1540944441 9932 195.159.176.226 (31 Oct 2018 00:07:21 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Wed, 31 Oct 2018 00:07:21 +0000 (UTC) User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.0.50 (windows-nt) To: emacs-devel@gnu.org Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Wed Oct 31 01:07:17 2018 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1gHe2X-0002WK-3q for ged-emacs-devel@m.gmane.org; Wed, 31 Oct 2018 01:07:17 +0100 Original-Received: from localhost ([::1]:56151 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gHe4d-0005xl-MD for ged-emacs-devel@m.gmane.org; Tue, 30 Oct 2018 20:09:27 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:37699) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gHe3w-0005xS-B5 for emacs-devel@gnu.org; Tue, 30 Oct 2018 20:08:45 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gHe3t-0004ek-3k for emacs-devel@gnu.org; Tue, 30 Oct 2018 20:08:44 -0400 Original-Received: from [195.159.176.226] (port=45127 helo=blaine.gmane.org) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1gHe3s-0004cE-SH for emacs-devel@gnu.org; Tue, 30 Oct 2018 20:08:41 -0400 Original-Received: from list by blaine.gmane.org with local (Exim 4.84_2) (envelope-from ) id 1gHe1h-0001eQ-K5 for emacs-devel@gnu.org; Wed, 31 Oct 2018 01:06:25 +0100 X-Injected-Via-Gmane: http://gmane.org/ Original-Lines: 25 Original-X-Complaints-To: usenet@blaine.gmane.org Cancel-Lock: sha1:ygW/pQxRTYh0JjQ+R4lb5DIM4XM= X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 195.159.176.226 X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.21 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" Xref: news.gmane.org gmane.emacs.devel:230863 Archived-At: On Tue 30 Oct 2018, Clément Pit-Claudel wrote: > On 30/10/2018 14.14, Alan Mackenzie wrote: >> Hello, Clément. > > Hey Alan :) > >> On Tue, Oct 30, 2018 at 11:05:55 -0400, Clément Pit-Claudel wrote: >>> On 30/10/2018 10.16, Andy Moreton wrote: >>>> How are users meant to write reliable code using such constructs ? >> >>> Ensure that the pattern actually matches :) >> >> You mean, unless you can be 100% sure that the pattern will match, you >> mustn't use pcase-... constructs. That sounds equivalent to saying you >> shouldn't use these constructs at all. > > That's an odd conclusion. It is a perfectly reasonable conclusion. `pcase-exhaustive' is available as a replacement for `pcase', but a similar exhaustive matcher that signals an error on pattern match failure is missing for all of the other pcase constructs. AndyM