Documentation

A mutable variable in the IO monad

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_

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'_

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

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

Lifted version of atomicWriteIORef.

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

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

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'

Lifted version of newIORef.

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

Lifted version of readIORef.

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

Lifted version of writeIORef.

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