From: Okamsn via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
To: "João Távora" <joaotavora@gmail.com>,
"Stefan Kangas" <stefankangas@gmail.com>
Cc: 67611@debbugs.gnu.org, Stefan Monnier <monnier@iro.umontreal.ca>
Subject: bug#67611: [PATCH] Add a Pcase pattern `cl-lambda` equivalent to `cl-destructuring-bind`
Date: Fri, 12 Jan 2024 00:55:47 +0000 [thread overview]
Message-ID: <5a26a4ee-ba12-448b-9606-a09f9396d9ea@protonmail.com> (raw)
In-Reply-To: <CALDnm528OQYfensjv41CqOBV5c7FjJih7t9X2gXb5Q2zz6amwg@mail.gmail.com>
João Távora wrote:
> 4. Pcase integration is a "nice to have". In the provided tests, the
> new extension is only tested as a destructuring aid, so I cannot tell
> very well how it fares int the matching aspect of pcase. For example
> I did this experiment:
>
> (pcase (list 42 41 :c 42)
> ((cl-arglist (42 42 &key c))
> (list c))
> ((cl-arglist (42 b &rest more))
> (list b more)))
> ;; => (42 2)
> This matches the second case, which is good and returns (41 (:c 42))
>
> But how do I construct a case that matches only if the provided
> value to c is 42, if this is at all possible?
It is possible. You can give a pattern instead of a symbol for the
variable, but you have to use a version of `&key` variables in which the
pattern can't be confused for the normal `((KEY VAR) DEFAULT SUPPLIED)`
form. Please try the following:
;; => (42 2)
(pcase (list :c 42)
((cl-arglist (&key ((:c (and 43 c)))))
(list c 1))
((cl-arglist (&key ((:c (and 42 c)))))
(list c 2)))
;; => (42 2)
(pcase (list :c 42)
((cl-arglist (&key ((:c (and 43 c)))))
(list c 1))
((cl-arglist (&key ((:c (and (pred (equal 42))
c)))))
(list c 2))
((cl-arglist (&key ((:c (and 44 c)))))
(list c 3)))
next prev parent reply other threads:[~2024-01-12 0:55 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-12-03 20:33 bug#67611: [PATCH] Add a Pcase pattern `cl-lambda` equivalent to `cl-destructuring-bind` Okamsn via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-12-04 19:08 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-12-05 2:42 ` Okamsn via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-12-05 9:26 ` João Távora
2023-12-05 9:21 ` João Távora
2023-12-25 21:30 ` Okamsn via Bug reports for GNU Emacs, the Swiss army knife of text editors
2024-01-11 21:12 ` Stefan Kangas
2024-01-11 21:56 ` João Távora
2024-01-11 22:13 ` Stefan Kangas
2024-01-11 22:46 ` João Távora
2024-01-12 0:55 ` Okamsn via Bug reports for GNU Emacs, the Swiss army knife of text editors [this message]
2024-01-13 6:38 ` Stefan Kangas
2024-01-12 3:04 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2024-01-12 10:46 ` João Távora
2024-01-12 15:38 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2024-01-12 16:56 ` João Távora
2024-01-13 6:58 ` Stefan Kangas
2024-01-14 3:08 ` Richard Stallman
2024-01-14 3:12 ` João Távora
2024-01-17 3:29 ` Richard Stallman
2024-01-17 9:12 ` João Távora
2024-02-08 3:49 ` Richard Stallman
2024-02-08 13:41 ` João Távora
2024-02-11 3:28 ` Richard Stallman
2024-02-12 15:25 ` João Távora
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