channels.hs

module Main (main) where
 
import Control.Concurrent (forkIO, threadDelay)
import Control.Concurrent.Chan (Chan, newChan, writeChan, readChan)
import Control.Monad (forM_, replicateM)
 
baseDelay = 2000
writerDelay = 1 * baseDelay
readerDelay = 2 * baseDelay
 
writer :: Chan Int -> IO ()
writer c = forM_ [1..11] $ \i -> do
    threadDelay writerDelay
    writeChan c i
    putStrLn ("writer iteration: " ++ show i)
 
reader :: Chan Int -> IO ()
reader c = forM_ [1..10] $ \i -> do
    threadDelay readerDelay
    chanRes <- readChan c
    putStrLn ("reader iteration: " ++ show i ++ "; channel: " ++ show chanRes)
 
 
main = 
    do
    c      <- newChan
    _      <- forkIO $ writer c
    _      <- forkIO $ reader c
    threadDelay $ 30 * baseDelay
    result <- readChan c
    putStrLn (show result)