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Re: pcase docs
From: |
Michael Heerdegen |
Subject: |
Re: pcase docs |
Date: |
Sat, 23 Jan 2016 16:18:28 +0100 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/25.0.50 (gnu/linux) |
Eli Zaretskii <address@hidden> writes:
> So maybe we should drop everything and make sure those doc strings are
> corrected?
I think we have already made some good progress since then. But where
things are unclear, things should be improved further.
> > In the sense of pcase-defmacro, FUN, EXPR or the PATTERNs play the role
> > of arguments of the pattern.
>
> I don't think I see any of this in the doc string...
... of pcase-defmacro. You must read between the lines ;-)
Yes, it's missing.
> I expected to see its use like this:
>
> (map SOMETHING)
Indeed.
> But instead I see this:
>
> (pcase type
> (`list (map-pairs map))
> (`hash-table (map--into-hash-table map))
> (_ (error "Not a map type name: %S" type))))
> IOW, there's no 'map', which was defined with pcase-defmacro, but
> there are 'list' and 'hash-table', which weren't. And btw, why "`list"
> instead of "`(list"?
That's something completely unrelated to the pcase `map' pattern, just a
random usage of pcase. It's equivalent to
(cl-case type
((list) (map-pairs map))
((hash-table) (map--into-hash-table map))
(t (error "Not a map type name: %S" type)))
i.e., this just tests whether TYPE is bound to one of two constants.
A usage of the function `map-into' would look like:
(map-into '((1 . a) (2 . b)) 'hash-table)
==> an equivalent hash table to this alist
A usage of the pcase map pattern would look like this:
(pcase '((1 . a) (2 . b) (3 . c))
((map (2 x)) x))
==> b
Semantic and doc of the `map' pcase pattern are still a bit strange (or
wrong), I must say. I had hoped Nicolas would have time to improve the
doc a bit.
Michael.
- Re: pcase docs, (continued)
- Re: pcase docs, John Wiegley, 2016/01/22
- Re: pcase docs, Michael Heerdegen, 2016/01/22
- Re: pcase docs, Michael Heerdegen, 2016/01/22
- Re: pcase docs, Eli Zaretskii, 2016/01/22
- Re: pcase docs, Michael Heerdegen, 2016/01/23
- Re: pcase docs, Eli Zaretskii, 2016/01/23
- Re: pcase docs, Michael Heerdegen, 2016/01/23
- Re: pcase docs, Eli Zaretskii, 2016/01/23
- Re: pcase docs, Michael Heerdegen, 2016/01/23
- Re: pcase docs, Eli Zaretskii, 2016/01/23
- Re: pcase docs,
Michael Heerdegen <=
- Re: pcase docs, Nicolas Petton, 2016/01/24
- Re: pcase docs, Michael Heerdegen, 2016/01/23
- Re: pcase docs, Alan Mackenzie, 2016/01/23
- Re: pcase docs, Eli Zaretskii, 2016/01/23
- RE: pcase docs, Drew Adams, 2016/01/23
- Re: pcase docs, Stefan Monnier, 2016/01/24
- Re: pcase docs, Eli Zaretskii, 2016/01/22