setInterval.hs

-- ghc --make -O2 -threaded setInterval.hs
import Control.Concurrent (forkIO, putMVar, takeMVar,
                           newEmptyMVar, threadDelay)
import Control.Exception (finally)

setInterval :: IO a -> Int -> IO ()
setInterval action microsecs = do
    mvar <- newEmptyMVar
    _ <- forkIO $ loop `finally` putMVar mvar ()
    takeMVar mvar
  where loop = threadDelay microsecs >> action >> loop

main :: IO ()
main = setInterval (putStrLn "yolo") 1000000