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diff --git a/compiler/utils/FastFunctions.lhs b/compiler/utils/FastFunctions.lhs
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+Z%
+% (c) The University of Glasgow, 2000-2006
+%
+\section{Fast functions}
+
+\begin{code}
+
+module FastFunctions (
+    unsafeChr, inlinePerformIO, unsafeDupableInterleaveIO,
+    indexWord8OffFastPtr,
+    indexWord8OffFastPtrAsFastChar, indexWord8OffFastPtrAsFastInt,
+    global, Global
+  ) where
+
+#define COMPILING_FAST_STRING
+#include "HsVersions.h"
+
+import FastTypes
+import Data.IORef
+import System.IO.Unsafe
+
+#if defined(__GLASGOW_HASKELL__)
+
+import GHC.Exts
+import GHC.Word
+import GHC.IOBase (IO(..))
+--why not import it at __GLASGOW_HASKELL__==606 ?
+#if __GLASGOW_HASKELL__ >= 607
+import GHC.IOBase (unsafeDupableInterleaveIO)
+#endif
+import GHC.Base (unsafeChr)
+
+#if __GLASGOW_HASKELL__ < 607
+unsafeDupableInterleaveIO :: IO a -> IO a
+unsafeDupableInterleaveIO = unsafeInterleaveIO
+#endif
+
+-- Just like unsafePerformIO, but we inline it.
+{-# INLINE inlinePerformIO #-}
+inlinePerformIO :: IO a -> a
+inlinePerformIO (IO m) = case m realWorld# of (# _, r #)   -> r
+
+indexWord8OffFastPtr p i = W8# (indexWord8OffAddr# p i)
+indexWord8OffFastPtrAsFastChar p i = indexCharOffAddr# p i
+indexWord8OffFastPtrAsFastInt p i = word2Int# (indexWord8OffAddr# p i)
+-- or ord# (indexCharOffAddr# p i)
+
+#else /* ! __GLASGOW_HASKELL__ */
+
+import Foreign.Ptr
+import Data.Word
+
+-- hey, no harm inlining it, :-P
+{-# INLINE inlinePerformIO #-}
+inlinePerformIO :: IO a -> a
+inlinePerformIO = unsafePerformIO
+
+unsafeDupableInterleaveIO :: IO a -> IO a
+unsafeDupableInterleaveIO = unsafeInterleaveIO
+
+-- truly, these functions are unsafe: they assume
+-- a certain immutability of the pointer's target area.
+indexWord8OffFastPtr p i = inlinePerformIO (peekByteOff p n) :: Word8
+indexWord8OffFastPtrAsFastInt p i =
+  iUnbox (fromIntegral (inlinePerformIO (peekByteOff p n) :: Word8))
+indexWord8OffFastPtrAsFastChar p i =
+  fastChr (iUnbox (fromIntegral (inlinePerformIO (peekByteOff p n) :: Word8)))
+
+#endif /* ! __GLASGOW_HASKELL__ */
+
+--just so we can refer to the type clearly in a macro
+type Global a = IORef a
+global :: a -> Global a
+global a = unsafePerformIO (newIORef a)
+
+indexWord8OffFastPtr :: FastPtr Word8 -> FastInt -> Word8
+indexWord8OffFastPtrAsFastChar :: FastPtr Word8 -> FastInt -> FastChar
+indexWord8OffFastPtrAsFastInt :: FastPtr Word8 -> FastInt -> FastInt
+
+\end{code}