Data.IORef.MonadIO

Overloads the standard operations on IORefs, as defined in Data.IORef. This module is name-for-name swappable with Data.IORef unless ghc-specific operations like weak pointers are used.

The standard operations on IORef (such as newIORef, or modifyIORef) are overloaded over the MonadIO class. A monad m is declared an instance of MonadIO by defining a function

liftIO :: IO a -> m a

Documentation

class Monad m => MonadIO (m :: * -> *) where

Monads in which IO computations may be embedded. Any monad built by applying a sequence of monad transformers to the IO monad will be an instance of this class.

Instances should satisfy the following laws, which state that liftIO is a transformer of monads:

• liftIO . return = return

• liftIO (m >>= f) = liftIO m >>= (liftIO . f)

Minimal complete definition

liftIO

Methods

liftIO :: IO a -> m a

Lift a computation from the IO monad.

Instances

MonadIO IO

Since: 4.9.0.0

Methods

liftIO :: IO a -> IO a

data IORef a :: * -> *

A mutable variable in the IO monad

Instances

Eq (IORef a)

Since: 4.1.0.0

Methods

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

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

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

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

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

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

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