Generalize "set" operations from Data.List
Dannyu NDos
ndospark320 at gmail.com
Thu Nov 1 03:22:28 UTC 2018
filter erases all elements not satisfying given predicate. deleteBy erases
only the first element satisfying given predicate.
2018년 11월 1일 (목) 12:17에 Vanessa McHale <vanessa.mchale at iohk.io>님이 작성:
> Isn't deleteBy achievable via a filter?
> On 10/31/18 10:03 PM, Dannyu NDos wrote:
>
> It would be more ineffecient if I had to convert my lists to Data.Sets ot
> Data.Maps every time... For small lists, the operations are simple and
> practical. This doesn't have anything with generalization of type
> signatures anyway.
>
> 2018년 11월 1일 (목) 11:58에 David Feuer <david.feuer at gmail.com>님이 작성:
>
>> I don't think it's really so great that Data.List has a bunch of
>> operations that are inefficient on lists.
>>
>> On Wed, Oct 31, 2018, 10:53 PM Dannyu NDos <ndospark320 at gmail.com wrote:
>>
>>> I've suffered from inconvenience due to the restricted type signature.
>>> I'll be very glad if such restrictions are lifted:
>>>
>>> deleteBy :: (a -> b -> Bool
>>> <http://hackage.haskell.org/package/base-4.12.0.0/docs/Data-Bool.html#t:Bool>)
>>> -> a -> [b] -> [b]
>>> deleteFirstsBy :: (a -> b -> Bool
>>> <http://hackage.haskell.org/package/base-4.12.0.0/docs/Data-Bool.html#t:Bool>)
>>> -> [a] -> [b] -> [b]
>>> intersectBy :: (a -> b -> Bool
>>> <http://hackage.haskell.org/package/base-4.12.0.0/docs/Data-Bool.html#t:Bool>)
>>> -> [a] -> [b] -> [a]
>>>
>>> I approve these versions because:
>>> 1. It makes more sense that the "usual" `delete` and `intersect`
>>> functions are specialization of the "By" operations, not the vice versa.
>>> 2. Data.Map.Lazy module from *containers* package has these kind of
>>> "By" operations.
>>>
>>> The previous discussion about this in Sep 2016 didn't make much
>>> conclusion, so let the discussion continue.
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>>>
>>
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