[Haskell-beginners] Problems with System-Eval-Haskell

Hi I am fairly new to haskell , I was trying to use Eval function in haskell but its giving me a problem , even the example code given in * http://www.cse.unsw.edu.au/~dons/hs-plugins/html/System-Eval-Haskell.html*http://www.cse.unsw.edu.au/%7Edons/hs-plugins/html/System-Eval-Haskell.html do i <- eval "1 + 6 :: Int" [] :: IO (Maybe Int) when (isJust i) $ putStrLn (show (fromJust i)) is not working for me , it gives following error on the commandline: Warning: -Onot is deprecated: Use -O0 instead and doesnt print 7 , i guess that is what is expected to be printed. Can any one point me in the right way how to use eval function ? Thanks Joe