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Re: Quick pcase question
From: |
Phillip Lord |
Subject: |
Re: Quick pcase question |
Date: |
Wed, 02 Mar 2016 17:25:30 +0000 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux) |
Michael Heerdegen <michael_heerdegen@web.de> writes:
> Eric Abrahamsen <eric@ericabrahamsen.net> writes:
>
>> But the fact is that pcase is (very complex and very useful) syntax
>> sugar. I just wrote a pcase clause that looks like:
>>
>> `((,(and f-string (pred stringp)) . ,(and class (pred symbolp)))
>> . ,(and regexp (pred stringp)))
>>
>> And that's kind of awful. The whole point of pcase should be concision,
>> but that looks pretty terrible.
>
> :-P
>
> Maybe separate the testing and the binding operations, like:
What about this?
(pcase tst
((and
`(symbolla . ,x)
(guard (stringp x)))
(message "cdr is a string: %s" x)))
It separates out the list destructure and the guard. It seems cleaner to
be because only the list appears to be backticked and then unquoted.
A nice addition to pcase would perhaps be automatic "and". So having a
list like so
(pcase tst
(`(symbolla . ,x)
(guard (stringp x)))
(message "cdr is a string: %s" x))
would automatically be interpreted as "and". Not sure if this works
syntactically, though.
Phil
- Quick pcase question, Eric Abrahamsen, 2016/03/02
- Re: Quick pcase question, Michael Heerdegen, 2016/03/02
- Re: Quick pcase question, Eric Abrahamsen, 2016/03/02
- Re: Quick pcase question, Michael Heerdegen, 2016/03/02
- Re: Quick pcase question, Eric Abrahamsen, 2016/03/02
- Re: Quick pcase question, Michael Heerdegen, 2016/03/02
- Re: Quick pcase question,
Phillip Lord <=
- Re: Quick pcase question, Eric Abrahamsen, 2016/03/02
- Re: Quick pcase question, Stefan Monnier, 2016/03/02
- Re: Quick pcase question, Phillip Lord, 2016/03/02
- Re: Quick pcase question, Eric Abrahamsen, 2016/03/02
- Re: Quick pcase question, Phillip Lord, 2016/03/03
Re: Quick pcase question, Phillip Lord, 2016/03/02