DavidA
I am having difficulty debugging a troublesome stack overflow, which I think might be related to calling unsafePerformIO from within the IO monad.
[...]
f x = unsafePerformIO $ do m <- randomRIO (1,2) return (m+x)
As a side note you don't need unsafePerformIO here. Instead you should implement something like iterateM: iterateM :: Monad m => (a -> m a) -> a -> m [a] or change the type of your timedIterateIO to: timedIterateIO :: Int -> (a -> IO a) -> a -> IO a Also to do the actual timing you can use concurrency with SampleVar, which is cleaner and probably also faster: timedIterateIO :: Int -> (a -> IO a) -> a -> IO a timedIterateIO time f x0 = do resultVar <- newSampleVar x0 tid <- forkIO $ iterateFunc resultVar x0 threadDelay time readSampleVar resultVar <* killThread tid where iterateFunc resultVar x0 = x0 `seq` do x1 <- f x0 writeSampleVar resultVar x1 iterateFunc resultVar x1 Greets, Ertugrul -- nightmare = unsafePerformIO (getWrongWife >>= sex) http://blog.ertes.de/