testsuite/tests/polykinds/T7238.hs


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{-# LANGUAGE ConstraintKinds, TypeFamilies #-}
module T7238 where

import GHC.Exts

class Pair p where
        type Ctxt p a :: Constraint
        l :: Ctxt p a => p a -> a

data Unit a = Unit

instance Pair Unit where
        type Ctxt Unit a = a ~ ()
        l _ = ()