I can't seem to figure out what the difference is between using evaluate (runST action) and stToIO action when in the IO monad and running something in ST...they seem to behave identically...are they? If they are, why do they have different type signatures (one is ST RealWorld a -> IO a, while the other is (forall s. ST s a) -> IO a)? - Hal -- Hal Daume III "Computer science is no more about computers | hdaume@isi.edu than astronomy is about telescopes." -Dijkstra | www.isi.edu/~hdaume