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{-# LANGUAGE MultiParamTypeClasses, FlexibleInstances #-}
-- Hugs (2001) diverges when evaluating main, unless (Monad m) is
-- added as an extra superclass to C2, which should not be necessary.
module Main where
class Monad m => C1 m x
class (C1 m x) => C2 m x where
c2 :: x -> m x
instance Monad m => C1 m Bool
instance C2 Maybe Bool where
c2 = return
test :: Maybe Bool
test = c2 True
main = print test
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