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{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE GeneralizedNewtypeDeriving #-}
{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE PolyKinds #-}
module T11732c where
import Data.Kind
class Cat k (cat :: k -> k -> *) where
catId :: cat a a
catComp :: cat b c -> cat a b -> cat a c
instance Cat * (->) where
catId = id
catComp = (.)
newtype Fun2 a b = Fun2 (a -> b) deriving (Cat *)
-- The ticket says this should work:
-- newtype Fun1 a b = Fun1 (a -> b) deriving (Cat k)
-- But that requires that the kind of (Cat k) to depend on k, where k is local
-- This is all due for an update, anyway, when #14331 is done, and it's unclear
-- what the correct behavior here is, anyway. (Richard thinks: reject!)
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