Safe Haskell	Safe-Inferred
Language	Haskell98

Exception

Synopsis

Documentation

module Control.Exception

catchIO :: IO a -> (IOException -> IO a) -> IO a Source

handleIO :: (IOException -> IO a) -> IO a -> IO a Source

tryIO :: IO a -> IO (Either IOException a) Source

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.

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

ExceptionMonad IO
ExceptionMonad Ghc
ExceptionMonad m => ExceptionMonad (GhcT m)

gtry :: (ExceptionMonad m, Exception e) => m a -> m (Either e a) Source

ghandle :: (ExceptionMonad m, Exception e) => (e -> m a) -> m a -> m a Source

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

gonException :: ExceptionMonad m => m a -> m b -> m a Source

Always executes the first argument. If this throws an exception the second argument is executed and the exception is raised again.