GNU bug report logs - #71503
30.0.50; pcase-lambda (with "and" and "guard") does not work as expected

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Package: emacs;

Reported by: Mekeor Melire <mekeor <at> posteo.de>

Date: Wed, 12 Jun 2024 08:42:01 UTC

Severity: normal

Found in version 30.0.50

Done: Philip Kaludercic <philipk <at> posteo.net>

Bug is archived. No further changes may be made.

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Mekeor Melire <mekeor <at> posteo.de>
To: bug-gnu-emacs <at> gnu.org
Subject: 30.0.50; pcase-lambda (with "and" and "guard") does not work as
 expected
Date: Wed, 12 Jun 2024 08:40:54 +0000

I was expecting these two expressions to evaluate to the same value.
First, we call `pcase' on a value with a pattern involving `and' and
`guard':

    (pcase "value"
      ((and v (guard (string= "not-value" v))) v))
    ;; => nil

Second, let's use the same value and pattern, but this time using
`pcase-lambda':

    (funcall
      (pcase-lambda
        ((and v (guard (string= "not-value" v)))) v)
      "value")
    ;; => "value"

Am I missing something or is this a bug?

In GNU Emacs 30.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version
3.24.41, cairo version 1.16.0).
This bug report was last modified 1 year and 21 days ago.

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