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Concurrent hello world in Haskell
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module Main (main) where | |
import Control.Concurrent | |
main :: IO () | |
main = do | |
codechan <- newEmptyMVar | |
wait <- newEmptyMVar | |
myid <- myThreadId | |
putStrLn $ "I'm " ++ show myid | |
cid <- forkIO $ child codechan wait | |
let code = putStrLn ("Hello, " ++ show cid ++ "!") | |
putMVar codechan code | |
takeMVar wait | |
child :: MVar (IO ()) -> MVar () -> IO () | |
child codechan wait = do | |
myid <- myThreadId | |
putStrLn $ "I'm " ++ show myid | |
code <- takeMVar codechan | |
code | |
putMVar wait () |
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