Concurrency.TVar

TVar

data TVar a

Shared memory locations that support atomic memory transactions.

Instances

Eq (TVar a)

Since: base-4.8.0.0

Defined in GHC.Conc.Sync

Methods

(==) :: TVar a -> TVar a -> Bool

(/=) :: TVar a -> TVar a -> Bool

PrimUnlifted (TVar a)

Since: primitive-0.6.4.0

Defined in Data.Primitive.UnliftedArray

Methods

toArrayArray# :: TVar a -> ArrayArray#

fromArrayArray# :: ArrayArray# -> TVar a

newTVar :: a -> STM (TVar a)

Create a new TVar holding a value supplied

newTVarIO :: MonadIO m => a -> m (TVar a)

Lifted version of newTVarIO

Since: unliftio-0.2.1.0

readTVar :: TVar a -> STM a

Return the current value stored in a TVar.

readTVarIO :: MonadIO m => TVar a -> m a

Lifted version of readTVarIO

Since: unliftio-0.2.1.0

writeTVar :: TVar a -> a -> STM ()

Write the supplied value into a TVar.

modifyTVar :: TVar a -> (a -> a) -> STM ()

Mutate the contents of a TVar. N.B., this version is non-strict.

Since: stm-2.3

modifyTVar' :: TVar a -> (a -> a) -> STM ()

Strict version of modifyTVar.

Since: stm-2.3

stateTVar :: TVar s -> (s -> (a, s)) -> STM a

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

swapTVar :: TVar a -> a -> STM a

Swap the contents of a TVar for a new value.

Since: stm-2.3

mkWeakTVar :: MonadUnliftIO m => TVar a -> m () -> m (Weak (TVar a))

Lifted version of mkWeakTVar

Since: unliftio-0.2.1.0