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Re: [Emacs-diffs] master 387e1e1: New version of `seq-let' based on a pc
From: |
Nicolas Petton |
Subject: |
Re: [Emacs-diffs] master 387e1e1: New version of `seq-let' based on a pcase pattern |
Date: |
Mon, 11 May 2015 23:13:14 +0200 |
Stefan Monnier writes:
>> Yes. My idea of it was that you bind a sequence like the following:
>> (seq [a b [c d]])
>
> I was thinking of (seq a b (seq c d)).
>
> You could add support for (seq a b [c d]), if you want since that
> currently wouldn't collide with any pcase pattern, tho I'm not sure it's
> worth the added complexity for the user.
>
>> But then how can I have `seq-let' work the way it did until now? For
>> instance:
>> (seq-let [a [b [c]]] my-vector
>> ...)
>
> You expand [a [b [c]]] to (seq a (seq b (seq c))) before passing it to
> pcase-let.
>
>>>> + (push `(app (seq--reverse-args #'seq--nested-elt
>>>> + (reverse (cons ,index
>>>> ',nested-indexes)))
>>>> + ,name)
>>> This reverse plus seq--reverse-args business seems
>>> hideously inefficient. Why do you need that?
>> because of the way the `app' pattern works. Or maybe I'm missing
>> something?
>
> Why wouldn't
>
> `(app (seq--nested-elt ',(reverse (cons index nested-indexes))) ,name)
>
> work as well? Or, once you get rid of the nested case,
>
> `(app (seq-elt ,index) ,name)
I understand what you meant now. It indeed makes sense, and the pcase
pattern would be much more consistent. I'll push another commit.
Cheers,
Nico
>
>
> -- Stefan
--
Nicolas Petton
http://nicolas-petton.fr
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