From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Spencer Baugh Newsgroups: gmane.emacs.devel Subject: Re: Instead of pcase Date: Thu, 16 Nov 2023 10:20:49 -0500 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="40722"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Gnus/5.13 (Gnus v5.13) To: emacs-devel@gnu.org Cancel-Lock: sha1:/XMq/N8xSxWb1vRo7ksgikRHrOM= Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Thu Nov 16 17:44:56 2023 Return-path: Envelope-to: ged-emacs-devel@m.gmane-mx.org Original-Received: from lists.gnu.org ([209.51.188.17]) by ciao.gmane.io with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1r3fU7-000ATm-VO for ged-emacs-devel@m.gmane-mx.org; Thu, 16 Nov 2023 17:44:55 +0100 Original-Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1r3fTi-00008g-CU; Thu, 16 Nov 2023 11:44:30 -0500 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1r3eAt-00017T-DW for emacs-devel@gnu.org; Thu, 16 Nov 2023 10:20:59 -0500 Original-Received: from ciao.gmane.io ([116.202.254.214]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1r3eAs-0002lX-2p for emacs-devel@gnu.org; Thu, 16 Nov 2023 10:20:59 -0500 Original-Received: from list by ciao.gmane.io with local (Exim 4.92) (envelope-from ) id 1r3eAp-000AdP-V0 for emacs-devel@gnu.org; Thu, 16 Nov 2023 16:20:55 +0100 X-Injected-Via-Gmane: http://gmane.org/ Received-SPF: pass client-ip=116.202.254.214; envelope-from=ged-emacs-devel@m.gmane-mx.org; helo=ciao.gmane.io X-Spam_score_int: -16 X-Spam_score: -1.7 X-Spam_bar: - X-Spam_report: (-1.7 / 5.0 requ) BAYES_00=-1.9, HEADER_FROM_DIFFERENT_DOMAINS=0.25, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=no autolearn_force=no X-Spam_action: no action X-Mailman-Approved-At: Thu, 16 Nov 2023 11:44:29 -0500 X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.29 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-mx.org@gnu.org Original-Sender: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Xref: news.gmane.io gmane.emacs.devel:312812 Archived-At: Setting aside whether pcase is good or not: I've thought before that it would be nice to have a cond-let construct, like if-let and when-let. The body of a cond clause would be bound to the result of the condition. Perhaps that could be a good alternative to some use-cases for pcase? For example, if one has a cons whose cdr is a string if the car is 'foo, and whose cdr is a number if the car is 'bar, then with pcase one can write: (let ((exp (if t '(foo . "str") '(bar . 7)))) (pcase exp (`(foo . ,val) (concat "str" val)) (`(bar . ,val) (+ 1 val)))) and with cond-let one could write: (let ((exp (if t '(foo . "str") '(bar . 7)))) (cond-let ((val (and (eq (car exp) 'foo) (cdr exp))) (concat "str" val)) ((val (and (eq (car exp) 'bar) (cdr exp))) (+ 1 val)))) Which is maybe nicer?