Control.Monad.IO.Class

transformers-0.2.1.0: Concrete functor and monad transformers

Portability	portable
Stability	experimental
Maintainer	libraries@haskell.org

Description

Class of monads based on IO.

Synopsis

class Monad m => MonadIO m where

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)

Methods

liftIO :: IO a -> m a

Lift a computation from the IO monad.

Instances

MonadIO IO
MonadIO m => MonadIO (IdentityT m)
MonadIO m => MonadIO (ListT m)
MonadIO m => MonadIO (MaybeT m)
MonadIO m => MonadIO (ContT r m)
(Error e, MonadIO m) => MonadIO (ErrorT e m)
MonadIO m => MonadIO (ReaderT r m)
MonadIO m => MonadIO (StateT s m)
MonadIO m => MonadIO (StateT s m)
(Monoid w, MonadIO m) => MonadIO (WriterT w m)
(Monoid w, MonadIO m) => MonadIO (WriterT w m)
(Monoid w, MonadIO m) => MonadIO (RWST r w s m)
(Monoid w, MonadIO m) => MonadIO (RWST r w s m)

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