Hello. I'm trying to get some threads that I can stop and get last
values that was computed (and that values are IO values, in fact).
Here is my first approach:
module Main where
import Control.Concurrent (MVar, threadDelay, forkIO, newMVar,
putMVar, readMVar)
tick :: Int -> IO Int
tick v = return $ v + 1
loop :: MVar Bool -> a -> (a -> IO a) -> IO a
loop var init loopfun = do
next <- loopfun init
shouldStop <- readMVar var
case shouldStop of
True -> return next
False -> loop var next loopfun
runLoop :: Int -> IO ()
runLoop timeout = do
var <- newMVar False
forkIO $ threadDelay timeout >> putMVar var True
value <- loop var 0 tick
print value
main :: IO ()
main = runLoop 30000000
The problem is that it looks a little messy and what's worse it leaks
memory. So I'm wondering if there is a better approach to do so or
some fix to memory leak.
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