From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED!not-for-mail From: Eli Zaretskii Newsgroups: gmane.emacs.devel Subject: Re: Replace trivial pcase occurrences in the Emacs sources Date: Wed, 31 Oct 2018 22:05:26 +0200 Message-ID: <83a7mtj309.fsf@gnu.org> References: <83tvlcsnee.fsf@gnu.org> <20181029130132.GB4195@ACM> <20181029134722.GC4195@ACM> <87lg6gifnb.fsf@web.de> <87muqwxs7m.fsf@ericabrahamsen.net> <83h8h3jlyd.fsf@gnu.org> <8b897e43-679b-d38c-e185-0efe19c09342@yandex.ru> <83y3aei08p.fsf@gnu.org> <83o9bahz6i.fsf@gnu.org> <877ehyx7xg.fsf@web.de> <83d0rpj4y0.fsf@gnu.org> <871s85yjx9.fsf@web.de> NNTP-Posting-Host: blaine.gmane.org X-Trace: blaine.gmane.org 1541016283 27834 195.159.176.226 (31 Oct 2018 20:04:43 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Wed, 31 Oct 2018 20:04:43 +0000 (UTC) Cc: emacs-devel@gnu.org, monnier@IRO.UMontreal.CA, dgutov@yandex.ru To: Michael Heerdegen Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Wed Oct 31 21:04:38 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 1gHwjG-00077j-5F for ged-emacs-devel@m.gmane.org; Wed, 31 Oct 2018 21:04:38 +0100 Original-Received: from localhost ([::1]:33288 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gHwlM-0000Ud-Gl for ged-emacs-devel@m.gmane.org; Wed, 31 Oct 2018 16:06:48 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:57564) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gHwkN-0000T6-6K for emacs-devel@gnu.org; Wed, 31 Oct 2018 16:05:47 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gHwkI-0005bl-Jz for emacs-devel@gnu.org; Wed, 31 Oct 2018 16:05:47 -0400 Original-Received: from fencepost.gnu.org ([2001:4830:134:3::e]:42685) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gHwkE-0005Zp-Ns; Wed, 31 Oct 2018 16:05:40 -0400 Original-Received: from [176.228.60.248] (port=4999 helo=home-c4e4a596f7) by fencepost.gnu.org with esmtpsa (TLS1.2:RSA_AES_256_CBC_SHA1:256) (Exim 4.82) (envelope-from ) id 1gHwkA-00028j-Ts; Wed, 31 Oct 2018 16:05:36 -0400 In-reply-to: <871s85yjx9.fsf@web.de> (message from Michael Heerdegen on Wed, 31 Oct 2018 20:50:58 +0100) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 2001:4830:134:3::e 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:230911 Archived-At: > From: Michael Heerdegen > Cc: dgutov@yandex.ru, monnier@IRO.UMontreal.CA, emacs-devel@gnu.org > Date: Wed, 31 Oct 2018 20:50:58 +0100 > > Eli Zaretskii writes: > > > > I wouldn't call a `let' or `app' pattern that introduces a new binding > > > destructuring per se. OTOH, I would call a pattern using ` that tests > > > e.g. the car of the matched object with e.g. `pred' destructuring even > > > if that car is not bound to a variable. > > > > Can you give an example? I don't think I follow. > > (pcase '(1 2 3) > ((let a 3) a)) > ==> 3 Thanks, but I meant an example of what's described after the "OTOH". > To give an exact accurate definition is nearly impossible, however. That's not what I'm after. I'm after a definition that's usable and useful in practice, even if it has to be slightly inaccurate.