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{-# OPTIONS -fglasgow-exts  #-}


f :: Maybe (forall a. [a] -> [a]) -> Maybe ([Int], [Char])
f (Just g) = Just (g [3], g "hello")
f Nothing  = Nothing

main   = print $ f (Just reverse)
Success #stdin #stdout 0.02s 3544KB
stdin
Standard input is empty
stdout
Just ([3],"olleh")