stefan has pointed me a nice version: ============= ======================================================= randomInts :: IO [Int] randomInts = randoms `fmap` newStdGen main = do ints <- randomInts print $ take 5 ints =========== ========================================================= Anyway I'm curious why ============= ======================================================= module Main where import Data.Char import Control.Monad import Random import System.IO.Unsafe randomInts :: IO [Int] randomInts = unsafeInterleaveIO $ sequence $ cycle [unsafeInterleaveIO randomIO] main = do ints <- unsafeInterleaveIO randomInts print $ take 5 ints ============= ======================================================= doesn't return. Where did I miss another unsafeInerleaveIO to make it lazy enough? I still need a hint. Marc