Safe Haskell	Safe
Language	Haskell2010

Exception

Synopsis

module Control.Exception
class MonadIO m => ExceptionMonad m where
- gcatch :: Exception e => m a -> (e -> m a) -> m a
- gmask :: ((m a -> m a) -> m b) -> m b
- gbracket :: m a -> (a -> m b) -> (a -> m c) -> m c
- gfinally :: m a -> m b -> m a
catchIO :: IO a -> (IOException -> IO a) -> IO a
handleIO :: (IOException -> IO a) -> IO a -> IO a
tryIO :: IO a -> IO (Either IOException a)
gtry :: (ExceptionMonad m, Exception e) => m a -> m (Either e a)
ghandle :: (ExceptionMonad m, Exception e) => (e -> m a) -> m a -> m a
gonException :: ExceptionMonad m => m a -> m b -> m a

Documentation

module Control.Exception

class MonadIO m => ExceptionMonad m where Source #

A monad that can catch exceptions. A minimal definition requires a definition of gcatch .

Implementations on top of IO should implement gmask to eventually call the primitive mask . These are used for implementations that support asynchronous exceptions. The default implementations of gbracket and gfinally use gmask thus rarely require overriding.

Minimal complete definition

gcatch, gmask

Methods

gcatch :: Exception e => m a -> (e -> m a) -> m a Source #

Generalised version of catch , allowing an arbitrary exception handling monad instead of just IO .

gmask :: ((m a -> m a) -> m b) -> m b Source #

Generalised version of mask_ , allowing an arbitrary exception handling monad instead of just IO .

gbracket :: m a -> (a -> m b) -> (a -> m c) -> m c Source #

Generalised version of bracket , allowing an arbitrary exception handling monad instead of just IO .

gfinally :: m a -> m b -> m a Source #

Generalised version of finally , allowing an arbitrary exception handling monad instead of just IO .

Instances