| Copyright | (c) The University of Glasgow 2004 |
|---|---|
| License | BSD-style (see the file libraries/base/LICENSE) |
| Maintainer | libraries@haskell.org |
| Stability | experimental |
| Portability | non-portable (requires STM) |
| Safe Haskell | Trustworthy |
| Language | Haskell98 |
Control.Concurrent.STM.TVar
Contents
Description
TVar: Transactional variables
- data TVar a :: * -> *
- newTVar :: a -> STM (TVar a)
- newTVarIO :: a -> IO (TVar a)
- readTVar :: TVar a -> STM a
- readTVarIO :: TVar a -> IO a
- writeTVar :: TVar a -> a -> STM ()
- modifyTVar :: TVar a -> (a -> a) -> STM ()
- modifyTVar' :: TVar a -> (a -> a) -> STM ()
- swapTVar :: TVar a -> a -> STM a
- registerDelay :: Int -> IO (TVar Bool)
- mkWeakTVar :: TVar a -> IO () -> IO (Weak (TVar a))
TVars
data TVar a :: * -> *
Shared memory locations that support atomic memory transactions.
IO version of newTVar. This is useful for creating top-level
TVars using unsafePerformIO, because using
atomically inside unsafePerformIO isn't
possible.
readTVarIO :: TVar a -> IO a
Return the current value stored in a TVar. This is equivalent to
readTVarIO = atomically . readTVar
but works much faster, because it doesn't perform a complete
transaction, it just reads the current value of the TVar.
modifyTVar :: TVar a -> (a -> a) -> STM () Source
Mutate the contents of a TVar. N.B., this version is
non-strict.
modifyTVar' :: TVar a -> (a -> a) -> STM () Source
Strict version of modifyTVar.
registerDelay :: Int -> IO (TVar Bool)
Set the value of returned TVar to True after a given number of microseconds. The caveats associated with threadDelay also apply.