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{-# OPTIONS_GHC -fno-warn-redundant-constraints #-}
{-# LANGUAGE TypeFamilies #-}
module T4200 where
import Data.Kind (Type)
class C a where
type In a :: Type
op :: In a -> a -> Int
-- Should be ok; no -XUndecidableInstances required
instance (In c ~ Int) => C [c] where
type In [c] = In c
op _ _ = 3
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