|Basic concurrency stuff.|
|Forking and suchlike|
|forkIO :: IO () -> IO ThreadId|
The new thread will be a lightweight thread; if you want to use a foreign library that uses thread-local storage, use forkOS instead.
|forkOnIO :: Int -> IO () -> IO ThreadId|
|childHandler :: Exception -> IO ()|
|myThreadId :: IO ThreadId|
|Returns the ThreadId of the calling thread (GHC only).|
|killThread :: ThreadId -> IO ()|
killThread terminates the given thread (GHC only). Any work already done by the thread isn't lost: the computation is suspended until required by another thread. The memory used by the thread will be garbage collected if it isn't referenced from anywhere. The killThread function is defined in terms of throwTo:
killThread tid = throwTo tid (AsyncException ThreadKilled)
|throwTo :: ThreadId -> Exception -> IO ()|
throwTo raises an arbitrary exception in the target thread (GHC only).
throwTo does not return until the exception has been raised in the target thread. The calling thread can thus be certain that the target thread has received the exception. This is a useful property to know when dealing with race conditions: eg. if there are two threads that can kill each other, it is guaranteed that only one of the threads will get to kill the other.
If the target thread is currently making a foreign call, then the exception will not be raised (and hence throwTo will not return) until the call has completed. This is the case regardless of whether the call is inside a block or not.
|par :: a -> b -> b|
|pseq :: a -> b -> b|
|yield :: IO ()|
|The yield action allows (forces, in a co-operative multitasking implementation) a context-switch to any other currently runnable threads (if any), and is occasionally useful when implementing concurrency abstractions.|
|labelThread :: ThreadId -> String -> IO ()|
labelThread stores a string as identifier for this thread if you built a RTS with debugging support. This identifier will be used in the debugging output to make distinction of different threads easier (otherwise you only have the thread state object's address in the heap).
|threadDelay :: Int -> IO ()|
Suspends the current thread for a given number of microseconds (GHC only).
Note that the resolution used by the Haskell runtime system's internal timer is 1/50 second, and threadDelay will round its argument up to the nearest multiple of this resolution.
There is no guarantee that the thread will be rescheduled promptly when the delay has expired, but the thread will never continue to run earlier than specified.
|registerDelay :: Int -> IO (TVar Bool)|
|threadWaitRead :: Fd -> IO ()|
|Block the current thread until data is available to read on the given file descriptor (GHC only).|
|threadWaitWrite :: Fd -> IO ()|
|Block the current thread until data can be written to the given file descriptor (GHC only).|
|data MVar a|
|newMVar :: a -> IO (MVar a)|
|Create an MVar which contains the supplied value.|
|newEmptyMVar :: IO (MVar a)|
|Create an MVar which is initially empty.|
|takeMVar :: MVar a -> IO a|
There are two further important properties of takeMVar:
|putMVar :: MVar a -> a -> IO ()|
There are two further important properties of putMVar:
|tryTakeMVar :: MVar a -> IO (Maybe a)|
|A non-blocking version of takeMVar. The tryTakeMVar function returns immediately, with Nothing if the MVar was empty, or Just a if the MVar was full with contents a. After tryTakeMVar, the MVar is left empty.|
|tryPutMVar :: MVar a -> a -> IO Bool|
|A non-blocking version of putMVar. The tryPutMVar function attempts to put the value a into the MVar, returning True if it was successful, or False otherwise.|
|isEmptyMVar :: MVar a -> IO Bool|
Check whether a given MVar is empty.
Notice that the boolean value returned is just a snapshot of the state of the MVar. By the time you get to react on its result, the MVar may have been filled (or emptied) - so be extremely careful when using this operation. Use tryTakeMVar instead if possible.
|addMVarFinalizer :: MVar a -> IO () -> IO ()|
|Add a finalizer to an MVar (GHC only). See Foreign.ForeignPtr and System.Mem.Weak for more about finalizers.|
|data STM a|
|atomically :: STM a -> IO a|
Perform a series of STM actions atomically.
You cannot use atomically inside an unsafePerformIO or unsafeInterleaveIO. Any attempt to do so will result in a runtime error. (Reason: allowing this would effectively allow a transaction inside a transaction, depending on exactly when the thunk is evaluated.)
|retry :: STM a|
|Retry execution of the current memory transaction because it has seen values in TVars which mean that it should not continue (e.g. the TVars represent a shared buffer that is now empty). The implementation may block the thread until one of the TVars that it has read from has been udpated. (GHC only)|
|orElse :: STM a -> STM a -> STM a|
|Compose two alternative STM actions (GHC only). If the first action completes without retrying then it forms the result of the orElse. Otherwise, if the first action retries, then the second action is tried in its place. If both actions retry then the orElse as a whole retries.|
|catchSTM :: STM a -> (Exception -> STM a) -> STM a|
|Exception handling within STM actions.|
|data TVar a|
|newTVar :: a -> STM (TVar a)|
|Create a new TVar holding a value supplied|
|newTVarIO :: a -> IO (TVar a)|
|IO version of newTVar. This is useful for creating top-level TVars using unsafePerformIO, because using atomically inside unsafePerformIO isn't possible.|
|readTVar :: TVar a -> STM a|
|Return the current value stored in a TVar|
|writeTVar :: TVar a -> a -> STM ()|
|Write the supplied value into a TVar|
|unsafeIOToSTM :: IO a -> STM a|
|Unsafely performs IO in the STM monad.|
|ensureIOManagerIsRunning :: IO ()|
|Produced by Haddock version 0.8|