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Pitometsu/constraints.hs

Created March 13, 2020 20:50
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constraints family
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constraints.hs
{-# LANGUAGE DataKinds #-}
{-# LANGUAGE TypeOperators #-}
{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE ConstraintKinds #-}
{-# LANGUAGE PolyKinds #-}
import Data.Kind (Constraint)
type family All (c :: k -> Constraint) ts :: Constraint where All c '[] = (); All c (t:ts) = (c t, All c ts)
m :: (All Applicative '[a, b], All Traversable '[a, b]) => a x -> b x
m = undefined
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