[project @ 2005-02-02 14:54:18 by ross]

[ghc-base.git] / Control / Monad / ST.hs

diff --git a/Control/Monad/ST.hs b/Control/Monad/ST.hs
index 008dafc..0e34857 100644 (file)
--- a/Control/Monad/ST.hs
+++ b/Control/Monad/ST.hs
@@ -21,24 +21,29 @@ module Control.Monad.ST
        runST,          -- :: (forall s. ST s a) -> a
        fixST,          -- :: (a -> ST s a) -> ST s a
 
-       -- * Unsafe operations
-       unsafeInterleaveST,     -- :: ST s a -> ST s a
-       unsafeIOToST,           -- :: IO a -> ST s a
-
        -- * Converting 'ST' to 'IO'
        RealWorld,              -- abstract
-       stToIO                  -- :: ST RealWorld a -> IO a
+       stToIO,                 -- :: ST RealWorld a -> IO a
+
+       -- * Unsafe operations
+       unsafeInterleaveST,     -- :: ST s a -> ST s a
+       unsafeIOToST            -- :: IO a -> ST s a
       ) where
 
 import Prelude
 
 import Control.Monad.Fix
-import Data.Dynamic
+
+#include "Typeable.h"
 
 #ifdef __HUGS__
+import Data.Typeable
 import Hugs.ST
 import qualified Hugs.LazyST as LazyST
 
+INSTANCE_TYPEABLE2(ST,sTTc,"ST")
+INSTANCE_TYPEABLE0(RealWorld,realWorldTc,"RealWorld")
+
 fixST :: (a -> ST s a) -> ST s a
 fixST f = LazyST.lazyToStrictST (LazyST.fixST (LazyST.strictToLazyST . f))
 
@@ -48,26 +53,11 @@ unsafeInterleaveST =
 #endif
 
 #ifdef __GLASGOW_HASKELL__
-import GHC.ST
-import GHC.Base                ( unsafeCoerce#, RealWorld )
-import GHC.IOBase      ( IO(..), stToIO )
-
--- 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
+import GHC.ST          ( ST, runST, fixST, unsafeInterleaveST )
+import GHC.Base                ( RealWorld )
+import GHC.IOBase      ( stToIO, unsafeIOToST )
 #endif
 
 instance MonadFix (ST s) where
        mfix = fixST
 
--- ---------------------------------------------------------------------------
--- Typeable instance
-
-sTTc :: TyCon
-sTTc = mkTyCon "ST"
-
-instance (Typeable a, Typeable b) => Typeable (ST a b) where
-  typeOf st = mkAppTy sTTc [typeOf ((undefined :: ST a b -> a) st),
-                           typeOf ((undefined :: ST a b -> b) st)]