From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Stefan Monnier Newsgroups: gmane.emacs.devel Subject: Re: Code for cond* Date: Thu, 29 Feb 2024 13:07:20 -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="1208"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Gnus/5.13 (Gnus v5.13) Cc: emacs-devel@gnu.org To: Richard Stallman Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Thu Feb 29 19:08:32 2024 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 1rfkpc-000AaT-Cq for ged-emacs-devel@m.gmane-mx.org; Thu, 29 Feb 2024 19:08:32 +0100 Original-Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1rfkof-0004PZ-Bz; Thu, 29 Feb 2024 13:07:33 -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 1rfkoc-0004Oq-Ab for emacs-devel@gnu.org; Thu, 29 Feb 2024 13:07:30 -0500 Original-Received: from mailscanner.iro.umontreal.ca ([132.204.25.50]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1rfkoW-0000B7-GA; Thu, 29 Feb 2024 13:07:29 -0500 Original-Received: from pmg1.iro.umontreal.ca (localhost.localdomain [127.0.0.1]) by pmg1.iro.umontreal.ca (Proxmox) with ESMTP id 80A531000D6; Thu, 29 Feb 2024 13:07:22 -0500 (EST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=iro.umontreal.ca; s=mail; t=1709230041; bh=I6dSuTC08udNtH4ILA+Lf197e4Ioa3mMJd6cAzNNofk=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=m1SM4Xi79cKB/XtVM0aHNR1t9fHgSX4IjNR9mmjjYIUtX4HjTZ1tyEUYzdScghe5r 7QpSiPxV4XxMSuzhZJpNt4GeaWhcFMGI6h9J/GYMlNO3VQJQaGL4wBWeRzpsCk2JZj 9MWBBWtyoWws3SuuRqsTOY496GP6Ba+6a9xihx5iL7spbuaO8P8NQ8g+zd5OQQc3UH RXRXVN0IVTbo+kDhQJRxMzXttb09z7Qsh/3AkaXBWtiwO5wB25XsPDmpVDpLLAC5kl z1jo4HjFj1Gu3Km2lh7xmpaY6kvE+RHOB7BXcZDFB5F1uw490eqxsamsr/odQJRCdp GTpD1S+5BAm3A== Original-Received: from mail01.iro.umontreal.ca (unknown [172.31.2.1]) by pmg1.iro.umontreal.ca (Proxmox) with ESMTP id 7CBAF10004A; Thu, 29 Feb 2024 13:07:21 -0500 (EST) Original-Received: from alfajor (modemcable005.21-80-70.mc.videotron.ca [70.80.21.5]) by mail01.iro.umontreal.ca (Postfix) with ESMTPSA id 628F012051B; Thu, 29 Feb 2024 13:07:21 -0500 (EST) In-Reply-To: (Richard Stallman's message of "Wed, 28 Feb 2024 22:50:30 -0500") Received-SPF: pass client-ip=132.204.25.50; envelope-from=monnier@iro.umontreal.ca; helo=mailscanner.iro.umontreal.ca X-Spam_score_int: -42 X-Spam_score: -4.3 X-Spam_bar: ---- X-Spam_report: (-4.3 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, RCVD_IN_DNSWL_MED=-2.3, SPF_HELO_NONE=0.001, T_SCC_BODY_TEXT_LINE=-0.01, T_SPF_TEMPERROR=0.01 autolearn=ham autolearn_force=no X-Spam_action: no action 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:316648 Archived-At: > Maybe you are right, but I don't think I have seen an example of it. > Hmm, was this the purpose of proposing the cl-lambda pattern operator? No, see: (defmacro byte-optimize--pcase (exp &rest cases) ;; When we do ;; ;; (pcase EXP ;; (`(if ,exp ,then ,else) (DO-TEST)) ;; (`(plus ,e2 ,e2) (DO-ADD)) ;; (`(times ,e2 ,e2) (DO-MULT)) ;; ...) ;; ;; we usually don't want to fall back to the default case if ;; the value of EXP is of a form like `(if E1 E2)' or `(plus E1)' ;; or `(times E1 E2 E3)', instead we either want to signal an error ;; that EXP has an unexpected shape, or we want to carry on as if ;; it had the right shape (ignore the extra data and pretend the missing ;; data is nil) because it should simply never happen. ;; ;; The macro below implements the second option by rewriting patterns ;; like `(if ,exp ,then ,else)' ;; to `(if . (or `(,exp ,then ,else) pcase--dontcare))'. ;; ;; The resulting macroexpansion is also significantly cleaner/smaller/faster. [...]) in `byte-opt.el`. > Basically, I think allowing a shorter list is something that I think > would be desirable for one level of list structure whereas `cdr-safe' > seemed to make sense for nested levels. I can't think of places where it would make sense to apply something like `cdr-safe` to nested lists, so it's hard for me to judge. > > - As you say for "one specific list, it is hard to find anything simpler > > than `. ,_'", yet you added `cdr-safe` which applies to a single > > pattern, and thus typically to a single list, unless the pattern is > > a big (or ...) pattern which are rather unusual. > I can't follow that. Why do you say "typically to a single list"? I > don't think that is true -- it applies to all sublists of the pattern > used within it. Most patterns have a single list. As you see in `byte-optimize--pcase`, I need that kind of functionality for most/all branches. Stefan