| 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 | Haskell2010 |
Control.Concurrent.STM.TVar
Contents
Description
Synopsis
- 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 ()
- stateTVar :: TVar s -> (s -> (a, s)) -> STM a
- swapTVar :: TVar a -> a -> STM a
- registerDelay :: Int -> IO (TVar Bool)
- mkWeakTVar :: TVar a -> IO () -> IO (Weak (TVar a))
TVars
Shared memory locations that support atomic memory transactions.
newTVarIO :: a -> IO (TVar a) Source #
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 Source #
modifyTVar :: TVar a -> (a -> a) -> STM () Source #
Mutate the contents of a TVar. N.B., this version is
non-strict.
Since: stm-2.3
modifyTVar' :: TVar a -> (a -> a) -> STM () Source #
Strict version of modifyTVar.
Since: stm-2.3
stateTVar :: TVar s -> (s -> (a, s)) -> STM a Source #
Like modifyTVar' but the function is a simple state transition that can
return a side value which is passed on as the result of the STM.
Since: stm-2.5.0
registerDelay :: Int -> IO (TVar Bool) Source #
Switch the value of returned TVar from initial value False to True
after a given number of microseconds. The caveats associated with
threadDelay also apply.
Be careful not to exceed maxBound :: Int, which on 32-bit machines is only
2147483647 μs, less than 36 minutes.