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import Control.Concurrent
import Control.Monad
import GHC.Clock
import System.IO
import System.Posix.IO
import System.Timeout
main :: IO ()
main = do
(readPipe, _) <- createPipe
readPipeHandle <- fdToHandle readPipe
let nanoSecondsPerSecond = 1000 * 1000 * 1000
let milliSecondsPerSecond = 1000
let timeToSpend = 1
let timeToSpendNano = timeToSpend * nanoSecondsPerSecond
let timeToSpendMilli = timeToSpend * milliSecondsPerSecond
start <- getMonotonicTimeNSec
b <- hWaitForInput readPipeHandle timeToSpendMilli
end <- getMonotonicTimeNSec
let timeSpentNano = fromIntegral $ end - start
let delta = timeSpentNano - timeToSpendNano
-- We can never wait for a shorter amount of time than specified
putStrLn $ "delta >= 0: " ++ show (delta > 0)
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