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module Main where
class Show a => Foo a where
op :: a -> a
newtype Moose = MkMoose () deriving (Show, Eq, Ord)
newtype Noose = MkNoose () deriving (Ord)
instance Eq Noose where
a == b = False -- Non-standard!
f :: Ord a => a -> Bool
f x = x==x
main = do print (MkNoose () == MkNoose ()) -- Eq Noose
print (f (MkNoose ())) -- via Ord Noose
print (MkMoose () == MkMoose ()) -- Eq Moose
print (f (MkMoose ())) -- via Ord Moose
putStrLn (show (MkMoose ())) -- Should not use the show () method
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