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import Control.Concurrent (forkIO)
#if defined(STRICT)
import Control.Concurrent.Chan.Strict
#else
import Control.Concurrent.Chan
#endif
import System.Environment
-- Fork some computation processes, print their results
main = do
n <- getArgs >>= readIO . head
f1 <- run fibonacci
f2 <- run fibonacci2
mapM_ print . take n $ zip f1 f2
-- fork a process, return any messages it produces as a list
where
run f = do
c <- newChan
l <- getChanContents c
forkIO (writeList2Chan c f)
return l
--
-- very computationally expensive jobs:
fibonacci = map fib [0..]
fibonacci2 = map fib [1..] -- to defeat CSE
fib 0 = 0
fib 1 = 1
fib n = fib (n-1) + fib (n-2)
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