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{-# LANGUAGE TypeFamilies, GADTs #-}
{-# OPTIONS_GHC -fwarn-incomplete-patterns -fwarn-overlapping-patterns #-}
module PMC001 where
data family T a
data instance T [a] where
MkT1 :: T [Int]
MkT2 :: Char -> T [Char]
MkT3 :: T [a]
f :: T [a] -> T [a] -> Bool
f MkT1 MkT1 = True
f (MkT2 _) (MkT2 _) = True
f MkT3 MkT3 = True
g :: T [a] -> T [a] -> Bool
g x y
| MkT1 <- x, MkT1 <- y = True
| (MkT2 _) <- x, (MkT2 _) <- y = True
| MkT3 <- x, MkT3 <- y = True
|
