readFastMutInt, writeFastMutInt
) where
-#include "MachDeps.h"
+#ifdef __GLASGOW_HASKELL__
+#include "MachDeps.h"
#ifndef SIZEOF_HSINT
#define SIZEOF_HSINT INT_SIZE_IN_BYTES
#endif
-
import GHC.Base
import GHC.IOBase
+
+#else /* ! __GLASGOW_HASKELL__ */
+
+import Data.IORef
+
+#endif
+
+newFastMutInt :: IO FastMutInt
+readFastMutInt :: FastMutInt -> IO Int
+writeFastMutInt :: FastMutInt -> Int -> IO ()
\end{code}
\begin{code}
#ifdef __GLASGOW_HASKELL__
data FastMutInt = FastMutInt (MutableByteArray# RealWorld)
-newFastMutInt :: IO FastMutInt
newFastMutInt = IO $ \s ->
case newByteArray# size s of { (# s, arr #) ->
(# s, FastMutInt arr #) }
where I# size = SIZEOF_HSINT
-readFastMutInt :: FastMutInt -> IO Int
readFastMutInt (FastMutInt arr) = IO $ \s ->
case readIntArray# arr 0# s of { (# s, i #) ->
(# s, I# i #) }
-writeFastMutInt :: FastMutInt -> Int -> IO ()
writeFastMutInt (FastMutInt arr) (I# i) = IO $ \s ->
case writeIntArray# arr 0# i s of { s ->
(# s, () #) }
-\end{code}
+#else /* ! __GLASGOW_HASKELL__ */
+--maybe someday we could use
+--http://haskell.org/haskellwiki/Library/ArrayRef
+--which has an implementation of IOURefs
+--that is unboxed in GHC and just strict in all other compilers...
+newtype FastMutInt = FastMutInt (IORef Int)
+
+-- If any default value was chosen, it surely would be 0,
+-- so we will use that since IORef requires a default value.
+-- Or maybe it would be more interesting to package an error,
+-- assuming nothing relies on being able to read a bogus Int?
+-- That could interfere with its strictness for smart optimizers
+-- (are they allowed to optimize a 'newtype' that way?) ...
+-- Well, maybe that can be added (in DEBUG?) later.
+newFastMutInt = fmap FastMutInt (newIORef 0)
+
+readFastMutInt (FastMutInt ioRefInt) = readIORef ioRefInt
+
+-- FastMutInt is strict in the value it contains.
+writeFastMutInt (FastMutInt ioRefInt) i = i `seq` writeIORef ioRefInt i
#endif
+\end{code}