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kana-sama/listdot.hs

Created April 27, 2022 23:26
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  1. kana created this gist Apr 27, 2022.
    22 changes: 22 additions & 0 deletions listdot.hs
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    {-# LANGUAGE FlexibleInstances #-}
    {-# LANGUAGE FunctionalDependencies #-}
    {-# LANGUAGE MultiParamTypeClasses #-}

    class ListDot t a | t -> a where
    (•) :: ([a] -> [a]) -> a -> t

    instance ListDot ([a] -> [a]) a where
    (f • x) xs = f (x : xs)

    instance ListDot [a] a where
    f • x = f [x]

    list :: [a] -> [a]
    list = id

    x :: [Int]
    x =
    list
    • 1
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