Am Sonntag 24 Januar 2010 21:49:59 schrieb Matthias Güdemann:
Hi,
I wrote a program which should read the number of key presses in a given time. It forks a thread which calls getChar and increases a MVar each time getChar suceeds. After a delay (here 2s) the MVar is read, its value is printed and the program exits.
import Control.Concurrent
increaseEveryPush mVCount = do _ <- getChar inh <- takeMVar mVCount putMVar mVCount (inh + 1) increaseEveryPush mVCount
main = do x <- newMVar 0 forkIO (increaseEveryPush x) threadDelay 2000000 inh <- takeMVar x putStr $ "\n" ++ (show inh) ++ " times button pushed\n"
But this does not work, as getChar does not succeed if there is no EOF given (^D).
No, a newline would suffice. But you could set the buffering of stdin to NoBuffering. main = do hSetBuffering stdin NoBuffering x <- newMVar 0 forkIO (increaseEveryPush x) threadDelay 2000000 inh <- takeMVar x putStr $ "\n" ++ (show inh) ++ " times button pushed\n" $ ./keyPress uzfgoigzoruizhuiorhguioegu 26 times button pushed It probably won't work on Windows, though.
It normally just exits with 0 as value in the MVar. Is there a way toread the keyboard without having to terminate with EOF?
regards, Matthias