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|
{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE RankNTypes #-}
{-# OPTIONS_GHC -Wall #-}
module T10931 ( BugC(..) ) where
data IdT f a = IdC (f a)
class ( m ~ Outer m (Inner m) ) => BugC (m :: * -> *) where
type Inner m :: * -> *
type Outer m :: (* -> *) -> * -> *
bug :: ( forall n. ( n ~ Outer n (Inner n)
, Outer n ~ Outer m
)
=> Inner n a)
-> m a
instance BugC (IdT m) where
type Inner (IdT m) = m
type Outer (IdT _) = IdT
bug f = IdC f
|
