From: Stefan Monnier via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
To: Ihor Radchenko <yantar92@posteo.net>
Cc: Jim Porter <jporterbugs@gmail.com>, 68509@debbugs.gnu.org
Subject: bug#68509: 30.0.50; pcase-dolist matches backquote pattern incorrectly
Date: Mon, 19 Feb 2024 21:41:43 -0500 [thread overview]
Message-ID: <jwvle7fuau8.fsf-monnier+emacs@gnu.org> (raw)
In-Reply-To: <8734to8gov.fsf@localhost> (Ihor Radchenko's message of "Mon, 19 Feb 2024 18:14:24 +0000")
Ihor Radchenko [2024-02-19 18:14:24] wrote:
> Stefan Monnier <monnier@iro.umontreal.ca> writes:
>
>>> * lisp/emacs-lisp/pcase.el (pcase-dolist): Use `pcase' rather than
>>> `pcase-let*' to match the list elements. Update the docstring,
>>
>> That changes its behavior. It *will* break code.
>> This is basically not the same macro any more. Instead of being a macro
>> that iterates over all the elements of the list, it becomes a macro
>> which iterates only over the matching elements.
>
> Currently, the docstring states:
>
> PATTERN should be a `pcase' pattern describing the structure of
> LIST elements, and LIST is a list of objects that match PATTERN,
> i.e. have a structure that is compatible with PATTERN.
The doc for `pcase-let` is a bit more precise:
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.
> In my patch, I proposed to skip such elements.
> An alternative could be throwing an error.
As I said, what you propose is a *different* construct.
Maybe we should add some extra option/keyword to `pcase-dolist` to
indicate what to do with elements that don't match (such as signaling
an error, a warning, silently skipping it, ...).
Similar issues affect `pcase-let`, of course.
Stefan
next prev parent reply other threads:[~2024-02-20 2:41 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
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 [this message]
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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