Safe Haskell	None
Language	Haskell2010

Control.Effect.Catch

Description

An effect that enables catching exceptions thrown from impure computations such as IO.

Use of the Error effect from Control.Effect.Error may lead to simpler code, as well as avoiding the dynamically-typed nature of Exception. This is best used when integrating with third-party libraries that operate in IO. If you are using catch for resource management, consider using Resource instead.

Synopsis

data Catch m k = Exception e => CatchIO (m output) (e -> m output) (output -> k)
catch :: (Member Catch sig, Carrier sig m, Exception e) => m a -> (e -> m a) -> m a
catchSync :: (Member Catch sig, Carrier sig m, Exception e, MonadIO m) => m a -> (e -> m a) -> m a
runCatch :: (forall x. m x -> IO x) -> CatchC m a -> m a
withCatch :: MonadUnliftIO m => CatchC m a -> m a
newtype CatchC m a = CatchC {
- runCatchC :: ReaderC (Handler m) m a
}

Documentation

data Catch m k Source #

Constructors

Exception e => CatchIO (m output) (e -> m output) (output -> k)

Instances

Effect Catch Source #
Instance details Defined in Control.Effect.Catch Methods handle :: Functor f => f () -> (forall x. f (m x) -> n (f x)) -> Catch m (m a) -> Catch n (n (f a))
HFunctor Catch Source #
Instance details Defined in Control.Effect.Catch Methods fmap' :: (a -> b) -> Catch m a -> Catch m b hmap :: (forall x. m x -> n x) -> Catch m a -> Catch n a
Functor (Catch m) Source #
Instance details Defined in Control.Effect.Catch Methods fmap :: (a -> b) -> Catch m a -> Catch m b # (<$) :: a -> Catch m b -> Catch m a #
(Carrier sig m, MonadIO m) => Carrier (Catch :+: sig) (CatchC m) Source #
Instance details Defined in Control.Effect.Catch Methods eff :: (Catch :+: sig) (CatchC m) (CatchC m a) -> CatchC m a

catch :: (Member Catch sig, Carrier sig m, Exception e) => m a -> (e -> m a) -> m a Source #

Like catchError, but delegating to catch under the hood, which allows catching errors that might occur when lifting IO computations. Unhandled errors are rethrown. Use SomeException if you want to catch all errors.

catchSync :: (Member Catch sig, Carrier sig m, Exception e, MonadIO m) => m a -> (e -> m a) -> m a Source #

Like catch, but the handler only engages on synchronous exceptions. Async exceptions are rethrown.

runCatch :: (forall x. m x -> IO x) -> CatchC m a -> m a Source #

Evaluate a Catch effect.

withCatch :: MonadUnliftIO m => CatchC m a -> m a Source #

Evaluate a Catch effect, using MonadUnliftIO to infer a correct unlifting function.

newtype CatchC m a Source #

Constructors

CatchC
Fields runCatchC :: ReaderC (Handler m) m a

Instances

Monad m => Monad (CatchC m) Source #
Instance details Defined in Control.Effect.Catch Methods (>>=) :: CatchC m a -> (a -> CatchC m b) -> CatchC m b # (>>) :: CatchC m a -> CatchC m b -> CatchC m b # return :: a -> CatchC m a # fail :: String -> CatchC m a #
Functor m => Functor (CatchC m) Source #
Instance details Defined in Control.Effect.Catch Methods fmap :: (a -> b) -> CatchC m a -> CatchC m b # (<$) :: a -> CatchC m b -> CatchC m a #
Applicative m => Applicative (CatchC m) Source #
Instance details Defined in Control.Effect.Catch Methods pure :: a -> CatchC m a # (<>) :: CatchC m (a -> b) -> CatchC m a -> CatchC m b # liftA2 :: (a -> b -> c) -> CatchC m a -> CatchC m b -> CatchC m c # (>) :: CatchC m a -> CatchC m b -> CatchC m b # (<*) :: CatchC m a -> CatchC m b -> CatchC m a #
MonadIO m => MonadIO (CatchC m) Source #
Instance details Defined in Control.Effect.Catch Methods liftIO :: IO a -> CatchC m a #
MonadUnliftIO m => MonadUnliftIO (CatchC m) Source #
Instance details Defined in Control.Effect.Catch Methods askUnliftIO :: CatchC m (UnliftIO (CatchC m)) withRunInIO :: ((forall a. CatchC m a -> IO a) -> IO b) -> CatchC m b
(Carrier sig m, MonadIO m) => Carrier (Catch :+: sig) (CatchC m) Source #
Instance details Defined in Control.Effect.Catch Methods eff :: (Catch :+: sig) (CatchC m) (CatchC m a) -> CatchC m a