streamly/examples/nested-loops.hs

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2017-07-14 08:39:21 +03:00
import Control.Applicative ((<|>), empty)
import Control.Concurrent (myThreadId)
import Control.Monad.IO.Class (liftIO)
import System.IO (stdout, hSetBuffering, BufferMode(LineBuffering))
import System.Random (randomIO)
import Asyncly
main = wait_ $ do
liftIO $ hSetBuffering stdout LineBuffering
x <- loop "A " 2
y <- loop "B " 2
liftIO $ myThreadId >>= putStr . show
>> putStr " "
>> print (x, y)
where
loop name n = do
rnd <- liftIO (randomIO :: IO Int)
let result = (name ++ show rnd)
repeat = if n > 1 then loop name (n - 1) else empty
in (return result) <|> repeat