| Copyright | (c) 2010 Galois Inc. |
|---|---|
| License | BSD-style (see the file libraries/base/LICENSE) |
| Maintainer | John Launchbury, john@galois.com |
| Stability | experimental |
| Portability | IO |
| Safe Haskell | Safe |
| Language | Haskell98 |
Data.IORef.MonadIO
Description
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
Synopsis
- class Monad m => MonadIO (m :: * -> *) where
- data IORef a
- 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
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:
Minimal complete definition
A mutable variable in the IO monad
writeIORef :: MonadIO io => IORef a -> a -> io () Source #
modifyIORef :: MonadIO io => IORef a -> (a -> a) -> io () Source #
atomicModifyIORef :: MonadIO io => IORef a -> (a -> (a, b)) -> io b Source #