Relude.Lifted.IORef

Lifted reexports from Data.IORef module.

Documentation

data IORef a

A mutable variable in the IO monad.

>>> import GHC.Internal.Data.IORef
>>> r <- newIORef 0
>>> readIORef r
0
>>> writeIORef r 1
>>> readIORef r
1
>>> atomicWriteIORef r 2
>>> readIORef r
2
>>> modifyIORef' r (+ 1)
>>> readIORef r
3
>>> atomicModifyIORef' r (\a -> (a + 1, ()))
>>> readIORef r
4

See also STRef and MVar.

Instances

NFData1 IORef

Since: deepseq-1.4.3.0

Defined in Control.DeepSeq

Methods

liftRnf :: (a -> ()) -> IORef a -> ()

NFData (IORef a)

NOTE: Only strict in the reference and not the referenced value.

Since: deepseq-1.4.2.0

Defined in Control.DeepSeq

Methods

rnf :: IORef a -> ()

Eq (IORef a)

Pointer equality.

@since base-4.0.0.0

Defined in GHC.Internal.IORef

Methods

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

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

atomicModifyIORef :: MonadIO m => IORef a -> (a -> (a, b)) -> m b

Lifted version of atomicModifyIORef.

>>> ref <- newIORef 42
>>> atomicModifyIORef ref (\a -> (a, a + 3))
45
>>> readIORef ref
42

• To avoid space-leaks, see atomicModifyIORef' for stricter updates
• If you are not interested in the return value, see atomicModifyIORef_

atomicModifyIORef' :: MonadIO m => IORef a -> (a -> (a, b)) -> m b

Lifted version of atomicModifyIORef'.

>>> ref <- newIORef 42
>>> atomicModifyIORef' ref (\a -> (a, a + 3))
45
>>> readIORef ref
42

• For lazier updates, see atomicModifyIORef
• If you are not interested in the return value, see atomicModifyIORef'_

atomicModifyIORef_ :: MonadIO m => IORef a -> (a -> a) -> m ()

Version of atomicModifyIORef that discards return value. Useful when you want to update IORef but not interested in the returning result.

>>> ref <- newIORef 42
>>> atomicModifyIORef_ ref (`div` 2)
>>> readIORef ref
21

Since: 0.7.0.0

atomicModifyIORef'_ :: MonadIO m => IORef a -> (a -> a) -> m ()

Version of atomicModifyIORef' that discards return value. Useful when you want to update IORef but not interested in the returning result.

>>> ref <- newIORef 42
>>> atomicModifyIORef'_ ref (`div` 2)
>>> readIORef ref
21

Since: 0.7.0.0

atomicWriteIORef :: MonadIO m => IORef a -> a -> m ()

Lifted version of atomicWriteIORef.

>>> ref <- newIORef 42
>>> atomicWriteIORef ref 45
>>> readIORef ref
45

modifyIORef :: MonadIO m => IORef a -> (a -> a) -> m ()

Lifted version of modifyIORef.

>>> ref <- newIORef 42
>>> modifyIORef ref (\a -> a + 6)
>>> readIORef ref
48

• To avoid space-leaks, see modifyIORef' for stricter updates
• For atomic updates, see atomicModifyIORef

modifyIORef' :: MonadIO m => IORef a -> (a -> a) -> m ()

Lifted version of modifyIORef'.

>>> ref <- newIORef 42
>>> modifyIORef' ref (\a -> a + 3)
>>> readIORef ref
45

• For lazier updates, see modifyIORef
• For atomic updates, see atomicModifyIORef'

newIORef :: MonadIO m => a -> m (IORef a)

Lifted version of newIORef.

>>> ref <- newIORef False
>>> :t ref
ref :: IORef Bool

readIORef :: MonadIO m => IORef a -> m a

Lifted version of readIORef.

>>> ref <- newIORef 42
>>> readIORef ref
42

writeIORef :: MonadIO m => IORef a -> a -> m ()

Lifted version of writeIORef.

>>> ref <- newIORef 42
>>> writeIORef ref 43
>>> readIORef ref
43