--- This relies on IO and ST having the same representation modulo the
--- constraint on the type of the state
---
-unsafeIOToST :: IO a -> ST s a
-unsafeIOToST (IO io) = ST $ \ s -> (unsafeCoerce# io) s
+#if defined(__GLASGOW_HASKELL__)
+import GHC.ST ( ST, runST, fixST, unsafeInterleaveST )
+import GHC.Base ( RealWorld )
+import GHC.IO ( stToIO, unsafeIOToST, unsafeSTToIO )
+#elif defined(__HUGS__)
+import Data.Typeable
+import Hugs.ST
+import qualified Hugs.LazyST as LazyST