[Haskell-cafe] How to fold on types?

Тимур Амиров timur.deteam at gmail.com
Tue Dec 25 10:59:24 CET 2012


Thinking from subway (: foldl ($) LongDef values ?

вторник, 25 декабря 2012 г. пользователь Тимур Амиров писал:

> Try folding over data type constructor with $?
>
> вторник, 25 декабря 2012 г. пользователь Magicloud Magiclouds писал:
>
>> Forgot to mention, solution without TemplateHaskell.
>>
>>
>> On Tue, Dec 25, 2012 at 4:59 PM, Magicloud Magiclouds <
>> magicloud.magiclouds at gmail.com> wrote:
>>
>>> Say I have things like:
>>>
>>> data LongDec = LongDef a b c ... x y z
>>> values = [ 'a', 'b', 'c', ... 'x', 'y', 'z' ]
>>>
>>> Now I want them to be "LongDef 'a' 'b' 'c' ... 'x' 'y' 'z'".
>>> In form, this is something like folding. But since the type changes, so
>>> code like following won't work:
>>>
>>> foldl (\def value -> def value) LongDef values
>>>
>>> Is it possible to do this in some way?
>>> --
>>> 竹密岂妨流水过
>>> 山高哪阻野云飞
>>>
>>> And for G+, please use magiclouds#gmail.com.
>>>
>>
>>
>>
>> --
>> 竹密岂妨流水过
>> 山高哪阻野云飞
>>
>> And for G+, please use magiclouds#gmail.com.
>>
>
>
> --
> Best
> Timur DeTeam Amirov
> Moscow, Russia
>
>

-- 
Best
Timur DeTeam Amirov
Moscow, Russia
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