Proposal: Num instance for (a -> b)

[Dannyu NDos]

I'm +1 on this, since it is conventional to write addition (and others)
over function as such in most math textbooks.

2018년 11월 11일 (일) 13:48에 Daniel Cartwright <chessai1996 at gmail.com>님이 작성:

> relevant reddit comment thread:
> https://www.reddit.com/r/haskell/comments/9vtis5/the_universe_of_discourse_i_hate_the_environment/e9f1lea?utm_source=reddit-android
>
> instance Num b => Num (a -> b) where
>   f + g = \x -> f x + g x
>   f * g = \x -> f x * g x
>   f - g = \x -> f x - g x
>   negate f = \x -> negate (f x)
>   abs f = \x -> abs (f x)
>   signum f = \x -> signum (f x)
>   fromInteger i = \x -> fromInteger (f x)
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