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{-# LANGUAGE ExtendedDefaultRules #-}
{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE DataKinds #-}
{-# LANGUAGE KindSignatures #-}
module T12924 where
import GHC.TypeLits
data A (b :: [Symbol]) = A deriving Show
-- Test that ExtendedDefaultRules defaults multiparameter typeclasses with only
-- one parameter of kind Type.
class Works a (b :: [Symbol]) where
works :: a -> A b
instance Works Integer a where
works _ = A
main :: IO ()
main = print (addA (works 5) (works 10)) -- :: A '[])
-- | Note argument types aren't concrete
addA :: A a -> A a -> A '[]
addA A A = A
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