Control.Effect.Error

Documentation

data Error exc m k

Constructors

Throw exc

Catch (m b) (exc -> m b) (b -> k)

Instances

Effect (Error exc)

Defined in Control.Effect.Error

Methods

handle :: Functor f => f () -> (forall x. f (m x) -> n (f x)) -> Error exc m (m a) -> Error exc n (n (f a))

HFunctor (Error exc)

Defined in Control.Effect.Error

Methods

fmap' :: (a -> b) -> Error exc m a -> Error exc m b

hmap :: (forall x. m x -> n x) -> Error exc m a -> Error exc n a

Functor (Error exc m)

Defined in Control.Effect.Error

Methods

fmap :: (a -> b) -> Error exc m a -> Error exc m b

(<$) :: a -> Error exc m b -> Error exc m a

(Carrier sig m, Effect sig, Monad m) => Carrier (Error e :+: sig) (ErrorC e m)

Defined in Control.Effect.Error

Methods

ret :: a -> ErrorC e m a

eff :: (Error e :+: sig) (ErrorC e m) (ErrorC e m a) -> ErrorC e m a

throwError :: (Member (Error exc) sig, Carrier sig m) => exc -> m a

Throw an error, escaping the current computation up to the nearest catchError (if any).

run (runError (throwError a)) == Left @Int @Int a

catchError :: (Member (Error exc) sig, Carrier sig m) => m a -> (exc -> m a) -> m a

Run a computation which can throw errors with a handler to run on error.

Errors thrown by the handler will escape up to the nearest enclosing catchError (if any).

run (runError (pure a `catchError` pure)) == Right a

run (runError (throwError a `catchError` pure)) == Right @Int @Int a

run (runError (throwError a `catchError` (throwError @Int))) == Left @Int @Int a

runError :: (Carrier sig m, Effect sig, Monad m) => Eff (ErrorC exc m) a -> m (Either exc a)

Run an Error effect, returning uncaught errors in Left and successful computations’ values in Right.

run (runError (pure a)) == Right @Int @Int a

newtype ErrorC e m a

Constructors

ErrorC

Fields

• runErrorC :: m (Either e a)

Instances

(Carrier sig m, Effect sig, Monad m) => Carrier (Error e :+: sig) (ErrorC e m)

Defined in Control.Effect.Error

Methods

ret :: a -> ErrorC e m a

eff :: (Error e :+: sig) (ErrorC e m) (ErrorC e m a) -> ErrorC e m a