From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Eli Zaretskii Newsgroups: gmane.emacs.bugs Subject: bug#72328: [PATCH] Nested backquote in pcase Date: Tue, 06 Aug 2024 14:13:35 +0300 Message-ID: <86o765q4yo.fsf@gnu.org> References: <87jzh62vtr.fsf@gmail.com> <877cd5k1ra.fsf@web.de> <871q3d347e.fsf@gmail.com> <877cd4rxqo.fsf@web.de> <867cd4ywnq.fsf@gnu.org> <87mslumpsw.fsf@gmail.com> <86msluuox9.fsf@gnu.org> <875xshn3km.fsf@gmail.com> <87cymo6wp9.fsf@web.de> <87v80gkmg7.fsf@gmail.com> <86ikwfqj9w.fsf@gnu.org> <87a5hqzrxg.fsf@gmail.com> Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="31812"; mail-complaints-to="usenet@ciao.gmane.io" Cc: michael_heerdegen@web.de, monnier@iro.umontreal.ca, 72328@debbugs.gnu.org To: Thuna Original-X-From: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane-mx.org@gnu.org Tue Aug 06 13:16:53 2024 Return-path: Envelope-to: geb-bug-gnu-emacs@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 1sbIBP-00082z-JR for geb-bug-gnu-emacs@m.gmane-mx.org; Tue, 06 Aug 2024 13:16:51 +0200 Original-Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1sbIBD-0003tZ-Qu; Tue, 06 Aug 2024 07:16:39 -0400 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 1sbIBC-0003q3-U3 for bug-gnu-emacs@gnu.org; Tue, 06 Aug 2024 07:16:38 -0400 Original-Received: from debbugs.gnu.org ([2001:470:142:5::43]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1sbIBC-0001fK-L0 for bug-gnu-emacs@gnu.org; Tue, 06 Aug 2024 07:16:38 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=debbugs.gnu.org; s=debbugs-gnu-org; h=References:In-Reply-To:From:Date:To:Subject; bh=+3TGKnhgbR3M7SbcINt2uEG0LYyFA7HLYyNoJpDXL3I=; b=YIm10QueogNU5M7GLlp22SdD/Gali/VBU/vRd6pbtoTTeSP5gO+jJMpBUSj5KwqHEeWWhD2XWVMCDlIs+zn1KW7mfL+lSXiOH+9FmRnNMJQdeAzwAm8xvW21Fvqk+On24zbLPhANQ6ikPOsAfb0+oXpMH7jOTOXXlwiSdxp5FtGE04T6v13h9z5ePoCoVwH8skm6hMiF6aZRxmveqk4bsT/Nw759hOHj5Mk/Tv+oxZ1MWCje/t0dP83G73bhWTJBuGIZCSd2qdH2pxxvNFSLKInUeOcM3Ar4uX97VrN59Kn4mdKyyS6IpUE8VUVh07mSU7kGiOPb44TxVoW++K8cNQ==; Original-Received: from Debian-debbugs by debbugs.gnu.org with local (Exim 4.84_2) (envelope-from ) id 1sbIBa-0000tM-9j for bug-gnu-emacs@gnu.org; Tue, 06 Aug 2024 07:17:02 -0400 X-Loop: help-debbugs@gnu.org Resent-From: Eli Zaretskii Original-Sender: "Debbugs-submit" Resent-CC: bug-gnu-emacs@gnu.org Resent-Date: Tue, 06 Aug 2024 11:17:02 +0000 Resent-Message-ID: Resent-Sender: help-debbugs@gnu.org X-GNU-PR-Message: followup 72328 X-GNU-PR-Package: emacs X-GNU-PR-Keywords: patch Original-Received: via spool by 72328-submit@debbugs.gnu.org id=B72328.17229430023371 (code B ref 72328); Tue, 06 Aug 2024 11:17:02 +0000 Original-Received: (at 72328) by debbugs.gnu.org; 6 Aug 2024 11:16:42 +0000 Original-Received: from localhost ([127.0.0.1]:60216 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1sbIBF-0000sJ-UY for submit@debbugs.gnu.org; Tue, 06 Aug 2024 07:16:42 -0400 Original-Received: from eggs.gnu.org ([209.51.188.92]:58560) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1sbIBE-0000rk-7d for 72328@debbugs.gnu.org; Tue, 06 Aug 2024 07:16:41 -0400 Original-Received: from fencepost.gnu.org ([2001:470:142:3::e]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1sbI8d-0001An-Mp; Tue, 06 Aug 2024 07:13:59 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=gnu.org; s=fencepost-gnu-org; h=References:Subject:In-Reply-To:To:From:Date: mime-version; bh=+3TGKnhgbR3M7SbcINt2uEG0LYyFA7HLYyNoJpDXL3I=; b=Ym471FHgxqFM x+gQm8mcs+AwIYRBXVyCq+TP3+XLpwi5dunxgMGIYNLHU3+ywCpZhpH07G59q/MGjUBNG/cjD24eF WWX4HDd0vvpPg+I2I/ZU3uQbHxVNSXYmU8dP1/J2A507rProTaVodi/9ZDu4OwoNDBjwDN5qxCa2E ndhGJI8qmLgHvvbglSLTbGbQUwc1UA2ivF3kVNiPdiYMt3/wj4nvjmhvuIL1VIEzDN0/Mq4Kv7bx2 rm1XF6bGrbp3DX/Y9+Gbwgs1rgS04YcvGAqoV+PYuOxxGfIVeykZtWooCmB2QaqzoPGjOHjbwl47x vaI8xrX+i4xDrkLwXjPbbQ==; In-Reply-To: <87a5hqzrxg.fsf@gmail.com> (message from Thuna on Mon, 05 Aug 2024 21:32:43 +0200) X-BeenThere: debbugs-submit@debbugs.gnu.org X-Mailman-Version: 2.1.18 Precedence: list X-BeenThere: bug-gnu-emacs@gnu.org List-Id: "Bug reports for GNU Emacs, the Swiss army knife of text editors" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane-mx.org@gnu.org Original-Sender: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane-mx.org@gnu.org Xref: news.gmane.io gmane.emacs.bugs:289821 Archived-At: > From: Thuna > Cc: michael_heerdegen@web.de, monnier@iro.umontreal.ca, 72328@debbugs.gnu.org > Date: Mon, 05 Aug 2024 21:32:43 +0200 > > >> Note that I do not believe that there are no people who would be > >> effected by this, positively or negatively. > > > > We've learned from bitter experience that such arguments are usually > > false. IOW, we don't really know enough to make such assertions. > > I think there is a misunderstanding. I am not saying that there isn't > anyone who would be effected by this, it is the opposite. I understand > that this will effect people, and I agree that at minimum there needs to > be a decent period where the current behavior is maintained but marked > as obsolete. How do you envision making such a behavior change in a way that will leave the current behavior still maintained (and obsolete)? > An indefinite feature-freeze is where I have a problem. Disagreeing with a specific change is not tantamount to an indefinite feature-freeze. It is quite possible that someone will come up with a different idea of a change, which we will be able to reconcile easier with the previous behavior. > >> (defun macroexp-null (exp) > >> "Return non-nil if EXP will always evaluate to nil. > >> This form does not take non-local exits or side-effects into account." > >> (pcase exp > >> ((or 'nil ''nil '#'nil '`nil ``,,(pred macroexp-null)) > >> t))) > >> > >> which without this change would read as: > >> > >> (defun macroexp-null (exp) > >> "Return non-nil if EXP will always evaluate to nil. > >> This form does not take non-local exits or side-effects into account." > >> (pcase exp > >> ((or 'nil ''nil '#'nil '`nil > >> `(,'\` (,'\, ,(pred macroexp-null)))) > >> t))) > > > > Thanks, now you just need to explain why you needed this code and what > > did its caller do to require this. > > I do not understand what you are asking for. Whether `macroexp-null' > should exist or not, what it is trying to do should be fairly clear, so > should the way in which it benefits from the changed behavior. I asked to explain _why_ you need this. Risking to say the obvious, a program exists to do some job, and a function like the above is therefore part of some larger job. We are asking you to describe the higher-level context, which we could then use to try to decide whether the need is important enough to justify the backward-incompatible change. > I also cannot provide any justification for this patch above and beyond > what I have already mentioned in my initial message: This patch > establishes a symmetry between pcase's backquote pattern and quasiquote, > which allows trivially matching against the result of a quasiquote form. We would like to hear reasons for wanting this. > I would appreciate it if you would state your opinion on this patch, > putting aside concerns of backwards compatibility for a moment. I am > working under the assumption that this is an improvement and is > desirable, yet I have not yet heard from you or Stefan as to whether you > see it that way or not. I believe Stefan did say that. Me, my only stake here is the concern of backwards compatibility, which is why I'm talking only about that. Thanks.