import GHC.Exts
import System.IO.Unsafe ( unsafeInterleaveIO )
+#if __GLASGOW_HASKELL__ >= 607
+import GHC.IOBase (unsafeDupableInterleaveIO)
+#else
+unsafeDupableInterleaveIO :: IO a -> IO a
+unsafeDupableInterleaveIO = unsafeInterleaveIO
+#endif
+
w2i x = word2Int# x
i2w x = int2Word# x
i2w_s x = (x :: Int#)
-- This is one of the most hammered bits in the whole compiler
mk_supply#
- = unsafeInterleaveIO (
+ = unsafeDupableInterleaveIO (
genSymZh >>= \ (I# u#) ->
mk_supply# >>= \ s1 ->
mk_supply# >>= \ s2 ->