Acme.Missiles

The launchMissiles action, as mentioned in:

• Beautiful concurrency, by Simon Peyton Jones, to appear in "Beautiful code", ed Greg Wilson, O'Reilly 2007. http://research.microsoft.com/en-us/um/people/simonpj/papers/stm/index.htm#beautiful

Documentation

launchMissiles :: IO ()

Cause serious international side effects.

Launching missiles in the STM monad

withMissilesDo :: IO a -> IO a

Perform initialization needed to launch missiles in the STM monad.

launchMissilesSTM :: STM ()

Launch missiles within an STM computation. Even if the memory transaction is retried, only one salvo of missiles will be launched.

Example:

import Acme.Missiles
import Control.Concurrent
import Control.Concurrent.STM

main :: IO ()
main = withMissilesDo $ do
    xv <- atomically $ newTVar (2 :: Int)
    yv <- atomically $ newTVar (1 :: Int)
    atomically $ do
        x <- readTVar xv
        y <- readTVar yv
        if x > y
            then launchMissilesSTM
            else return ()
    threadDelay 100000