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robinhouston/ab.hs

Created June 14, 2019 22:33
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ab.hs
data T = Two (T, T) | One T deriving (Eq, Show)
type X = Either (Either T T) ()
f :: Either X X -> Either (X, X) ()
f (Left (Left (Left (Two (t1, t2))))) = Left (Left (Left t1), Left (Left t2))
f (Right (Left (Left (Two (t1, t2))))) = Left (Left (Left t1), Left (Right t2))
f (Left (Left (Right (Two (t1, t2))))) = Left (Left (Right t1), Left (Left t2))
f (Right (Left (Right (Two (t1, t2))))) = Left (Left (Right t1), Left (Right t2))
f (Left (Left (Left (One t)))) = Left (Left (Left t), Right ())
f (Right (Left (Left (One t)))) = Left (Left (Right t), Right ())
f (Left (Left (Right (One t)))) = Left (Right (), Left (Left t))
f (Right (Left (Right (One t)))) = Left (Right (), Left (Right t))
f (Left (Right ())) = Left (Right (), Right ())
f (Right (Right ())) = Right ()
g :: Either (X, X) () -> Either X X
g (Left (Left (Left t1), Left (Left t2))) = Left (Left (Left (Two (t1, t2))))
g (Left (Left (Left t1), Left (Right t2))) = Right (Left (Left (Two (t1, t2))))
g (Left (Left (Right t1), Left (Left t2))) = Left (Left (Right (Two (t1, t2))))
g (Left (Left (Right t1), Left (Right t2))) = Right (Left (Right (Two (t1, t2))))
g (Left (Left (Left t), Right ())) = Left (Left (Left (One t)))
g (Left (Left (Right t), Right ())) = Right (Left (Left (One t)))
g (Left (Right (), Left (Left t))) = Left (Left (Right (One t)))
g (Left (Right (), Left (Right t))) = Right (Left (Right (One t)))
g (Left (Right (), Right ())) = Left (Right ())
g (Right ()) = Right (Right ())
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