From: Jim Porter <jporterbugs@gmail.com>
To: Ihor Radchenko <yantar92@posteo.net>, 68509@debbugs.gnu.org
Subject: bug#68509: 30.0.50; pcase-dolist matches backquote pattern incorrectly
Date: Tue, 16 Jan 2024 08:52:27 -0800 [thread overview]
Message-ID: <9bc2bd05-5fdb-9d5a-3d98-c344c7275027@gmail.com> (raw)
In-Reply-To: <87a5p5l3jm.fsf@localhost>
On 1/16/2024 7:07 AM, Ihor Radchenko wrote:
> Consider the following
>
> (pcase-dolist (`(,(and (pred stringp) a) .
> ,(and (pred stringp) b))
> '(("TODO") ("DONE" . "a")))
> (warn "%S :: %S" a b))
>
> Executing the above yields
>
> ⛔ Warning (emacs): "TODO" :: nil
> ⛔ Warning (emacs): "DONE" :: "a"
>
> even though ("TODO") does not match the pattern.
This isn't an issue with 'pcase-dolist', but rather a known/intentional
limitation of 'pcase-let':
(pcase-let ((`(,(and (pred stringp) a) .
,(and (pred stringp) b))
'("TODO")))
(warn "%S :: %S" a b))
-> Warning (emacs): "TODO" :: nil
The 'pcase-let' docstring says this:
> Each EXP should match (i.e. be of compatible structure) to its
> respective PATTERN; a mismatch may signal an error or may go
> undetected, binding variables to arbitrary values, such as nil.
I do think we should fix it somehow though. This behavior is extremely
confusing, and as much as I'm a fan of 'pcase', I'm emphatically *not* a
fan of how this part works.
next prev parent reply other threads:[~2024-01-16 16:52 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-16 15:07 bug#68509: 30.0.50; pcase-dolist matches backquote pattern incorrectly Ihor Radchenko
2024-01-16 16:52 ` Jim Porter [this message]
2024-01-16 18:43 ` Ihor Radchenko
2024-02-19 10:05 ` Ihor Radchenko
2024-02-19 12:59 ` Eli Zaretskii
2024-02-19 15:53 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2024-02-19 18:14 ` Ihor Radchenko
2024-02-20 2:41 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2024-02-20 13:40 ` Ihor Radchenko
2024-02-20 14:35 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2024-02-20 15:16 ` Ihor Radchenko
2024-02-20 17:51 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2024-02-21 11:23 ` Ihor Radchenko
2024-02-21 14:17 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2024-02-23 14:05 ` Ihor Radchenko
2024-02-23 14:58 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2024-02-24 13:28 ` Ihor Radchenko
2024-02-24 14:57 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2024-02-19 15:51 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2024-02-19 18:16 ` Ihor Radchenko
2024-02-20 2:46 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
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