GNU bug report logs - #68028
29.1; (elisp) `pcase Macro': move `rx' before SEQPAT description

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Package: emacs;

Reported by: Drew Adams <drew.adams <at> oracle.com>

Date: Mon, 25 Dec 2023 16:02:01 UTC

Severity: wishlist

Found in version 29.1

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From: Mattias Engdegård <mattiase <at> acm.org>
To: Stefan Kangas <stefankangas <at> gmail.com>
Cc: Stefan Monnier <monnier <at> iro.umontreal.ca>, Drew Adams <drew.adams <at> oracle.com>, 68028 <at> debbugs.gnu.org
Subject: bug#68028: 29.1; (elisp) `pcase Macro': move `rx' before SEQPAT description
Date: Thu, 28 Dec 2023 11:29:37 +0100

[Message part 1 (text/plain, inline)]
27 dec. 2023 kl. 22.47 skrev Stefan Kangas <stefankangas <at> gmail.com>:

>> Please consider moving the description of `rx' forms from after the
>> description of SEQPAT forms (`and' and `or').  The scope of the latter
>> description is less clear if `rx' follows the descriptions of `and' and
>> `or' (with no particular separation).  IOW, separate the SEQPAT
>> description from the other pattern descriptions better.
> 
> Mattias, since you added that part, do you have any thoughts?

The location of the `rx` pattern description is fine; it's the SEQPAT paragraph that causes trouble as it splits the table into two parts.

I suggest we remove that paragraph because it doesn't actually say anything useful at that point; the user can learn how `or` and `and` patterns work without knowing that they are SEQPATs. Actually, I'd hoist those two patterns and reorder them to keep patterns in a rough order of usage: something like

  pred, guard, or, and, let, app, rx

makes more sense -- `pred` and `guard` clearly belong together, `app` is less common than `let`.

We could explain SEQPAT in a short sentence somewhere else, either near the beginning of the node or further down in the 'Caveats' subsection. A simple (and probably flawed) patch attached.

Stefan M probably has a better sense of how to improve the text. (By the way, the caveat section says that sequencing patterns use `eq` for comparison. Don't they use `eql`?)


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This bug report was last modified 1 year and 168 days ago.

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