Hi all, in a compiler project I am using "global variables" of the form: gNewLabelNr :: IORef Int gNewLabelNr = unsafePerformIO $ newIORef 1 getAndUpdateVar var f = unsafePerformIO $ do oldVal <- readIORef var writeIORef var (f oldVal) return oldVal makeBlockName = "Block_" ++ show (getAndUpdateVar gNewLabelNr (+1)) (I know I could use a Monad to avoid this kind of unsafe programming, but I don't (didn't) want to rewrite existing code.) The problem is, that with optimizations turned on (using ghc V6.2.1) the label number is calulated only once, so each call to makeBlockName yields the same value. I tried a) adding a dummy parameter to makeBlockName and b) specifying an INLINE pragma to both getAndUpdateVar and makeBlockName, but that doesn't help. What can I do to prevent optimization to optimize that calculation away? Thanks, Bernd