From: Thuna <thuna.cing@gmail.com>
To: Eli Zaretskii <eliz@gnu.org>
Cc: michael_heerdegen@web.de, monnier@iro.umontreal.ca,
72328@debbugs.gnu.org
Subject: bug#72328: [PATCH] Nested backquote in pcase
Date: Mon, 05 Aug 2024 21:32:43 +0200 [thread overview]
Message-ID: <87a5hqzrxg.fsf@gmail.com> (raw)
In-Reply-To: <86ikwfqj9w.fsf@gnu.org>
>> 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. An indefinite feature-freeze is where I have a problem.
>> Very well. In that case, here's the original case which prompted me to
>> look into how pcase's backquote behaves:
>>
>> (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 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.
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.
next prev parent reply other threads:[~2024-08-05 19:32 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-07-28 0:40 bug#72328: [PATCH] Nested backquote in pcase Thuna
2024-07-28 14:52 ` Michael Heerdegen via Bug reports for GNU Emacs, the Swiss army knife of text editors
2024-07-28 15:51 ` Thuna
2024-07-28 16:02 ` Eli Zaretskii
2024-07-28 16:20 ` Thuna
2024-07-29 16:03 ` Michael Heerdegen via Bug reports for GNU Emacs, the Swiss army knife of text editors
2024-07-29 16:45 ` Eli Zaretskii
2024-07-30 7:45 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2024-08-03 0:07 ` Thuna
2024-08-03 5:59 ` Eli Zaretskii
2024-08-03 13:22 ` Thuna
2024-08-04 17:10 ` Michael Heerdegen via Bug reports for GNU Emacs, the Swiss army knife of text editors
2024-08-04 21:27 ` Thuna
2024-08-05 11:52 ` Eli Zaretskii
2024-08-05 19:32 ` Thuna [this message]
2024-08-06 8:21 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2024-08-06 11:13 ` Eli Zaretskii
2024-08-06 13:09 ` Thuna
2024-08-07 3:33 ` Michael Heerdegen via Bug reports for GNU Emacs, the Swiss army knife of text editors
2024-08-07 11:53 ` Eli Zaretskii
2024-08-07 17:34 ` Thuna
2024-08-08 5:57 ` Eli Zaretskii
2024-08-23 3:25 ` Michael Heerdegen via Bug reports for GNU Emacs, the Swiss army knife of text editors
2024-08-23 14:49 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2024-08-23 16:04 ` Eli Zaretskii
2024-08-23 19:11 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2024-08-23 19:29 ` Eli Zaretskii
2024-09-07 7:18 ` Eli Zaretskii
2024-09-07 12:24 ` Michael Heerdegen via Bug reports for GNU Emacs, the Swiss army knife of text editors
2024-08-23 20:19 ` Thuna
2024-07-29 17:43 ` Thuna
2024-07-29 19:05 ` Michael Heerdegen via Bug reports for GNU Emacs, the Swiss army knife of text editors
2024-07-29 20:45 ` Michael Heerdegen via Bug reports for GNU Emacs, the Swiss army knife of text editors
2024-07-29 20:59 ` Thuna
2024-07-30 17:53 ` Michael Heerdegen via Bug reports for GNU Emacs, the Swiss army knife of text editors
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