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

[João Távora]

On Wed, Jan 17, 2024 at 3:29 AM Richard Stallman <rms@gnu.org> wrote:

> Could you tell me more concretely what this proposed feature would
> look like in use?  Perhaps with an example including context?

Many examples in the patch, have you looked?

> pcase does not use lambda lists, and neither does cond*.

Pcase it extensible for any object structure the user may
think of you can think of. This proposal is an extension.

Here's an example

(pcase some-mistery-object
   ((cl-arglist (42 &key a b c))  ; this proposal
    (message "Oh, it starts it 42 and has c=%s" c))
   (`(,_ ,x ,_)
    (message "Boring three-element list with middle %s" x))
   (`[,_ ,x ,_]
    (message "Fancy vector with middle %s" x))
   ((franklinboing (nixneez)) ; my data-structure
    (message "This franklinboing has some nice nixneez %s=" nizneez)))

João