GNU bug report logs - #67611
[PATCH] Add a Pcase pattern `cl-lambda` equivalent to `cl-destructuring-bind`

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From: Okamsn <okamsn <at> protonmail.com>
To: Stefan Monnier <monnier <at> iro.umontreal.ca>
Cc: 67611 <at> debbugs.gnu.org, joaotavora <at> gmail.com
Subject: bug#67611: [PATCH] Add a Pcase pattern `cl-lambda` equivalent to `cl-destructuring-bind`
Date: Mon, 25 Dec 2023 21:30:07 +0000

[Message part 1 (text/plain, inline)]

Stefan Monnier wrote:
>> The attached patch adds the pattern `cl-lambda` for Pcase, which works
>> like `cl-destructuring-bind`. There are two differences with the lambda
>> lists:
> 
> Hmm... I'm not sure mixing the CL destructuring patterns with the Pcase
> patterns (both of which are rather featureful and complex) will help
> their popularity.
> 
> Beside that problem (which means I'm not very favorable to the
> addition), the name should be changed because "lambda" is misleading.
> It suggests this has to do with a function (I had to read the code to
> understand what this is doing).
> 
>> The pattern is useful when one wants to combine the features of `pcase`
>> and `cl-destructuring-bind`, such combining the optional values with the
>> `pred` or `guard` patterns.
> 
> Do you have examples uses?
> 
> Maybe we could introduce a different Pcase pattern which covers those
> needs but stays closer to the Pcase pattern syntax?
> 
> 
>          Stefan
> 

Hello,

Because I wrote this patch with the thought that others might want it, I 
don't have any nontrivial examples to share right now. The best example 
I have for the use of the optional arguments is for the implementing of 
the optional arguments, which isn't very convincing.

I've updated the patch to rename the pattern to `cl-arglist` and to 
avoid creating intermediate variables using the `let` pattern, but I'm 
fine with resting the discussion here until a stronger argument can be 
made in favor of the patch.

Thank you.

[v2-0001-Add-the-Pcase-pattern-cl-arglist-for-matching-a-C.patch (text/x-patch, attachment)]

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