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Re: Quick pcase question
From: |
Eric Abrahamsen |
Subject: |
Re: Quick pcase question |
Date: |
Thu, 03 Mar 2016 09:13:45 +0800 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/25.1.50 (gnu/linux) |
phillip.lord@russet.org.uk (Phillip Lord) writes:
> 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)))
That seems quite a bit better -- I really haven't yet wrapped my head
around the possible permutations of upatterns and qpatterns. Still a bit
ungainly when you have multiple clauses, but it does look a little more
intuitive.
Thanks to you both!
E
- 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, 2016/03/02
- Re: Quick pcase question,
Eric Abrahamsen <=
- 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