Why can I run (runghc) some Haskell scripts but I cannot seem to compile them? e.g. http://www.haskell.org/all_about_monads/examples/example25.hs I've changed the import listing to the following: import IO import System import Monad import Data.Maybe import Data.List import Data.Char (toLower) import Control.Monad.State import Control.Monad.Writer The compiler errors are like the following: N-Queens.o:fake:(.text+0x2fe): undefined reference to `mtlzm1zi1zi0zi2_Controlzi MonadziStateziLazzy_zdf9_closure' N-Queens.o:fake:(.text+0x422): undefined reference to `mtlzm1zi1zi0zi2_Controlzi MonadziStateziLazzy_zdf7_closure' N-Queens.o:fake:(.text+0x66f6): undefined reference to `mtlzm1zi1zi0zi2_Controlz iMonadziWriterziLazzy_zdf1_closure' -- Regards, Casey