{-# LANGUAGE RankNTypes, FlexibleInstances #-} -- This one made ghc-4.08 crash -- rename/RnEnv.lhs:239: Non-exhaustive patterns in function get_tycon_key -- The type in the Monad instance is utterly bogus, of course module ShouldCompile ( Set ) where data Set a = Set [a] deriving (Eq, Ord, Read, Show) {- instance Functor Set where f `fmap` (Set xs) = Set $ f `fmap` xs -} instance Monad (forall a. Eq a => Set a) where return x = Set [x] {- instance Eq (forall a. [a]) where -}