Copyright	(c) 2023 Sayo Koyoneda
License	MPL-2.0 (see the file LICENSE)
Maintainer	[email protected]
Safe Haskell	None
Language	GHC2021

Data.Effect.Except

Description

An effect to escape from the normal control structure with an exception value in the middle of a context.

Synopsis

data Throw e a where
- Throw :: forall e a. e -> Throw e a
data Catch e (f :: Type -> Type) a where
- Catch :: forall (f :: Type -> Type) a e. f a -> (e -> f a) -> Catch e f a
type LThrow e = LiftFOE (Throw e)
pattern LThrow :: forall a e f a1. () => forall. (a ~ a1, ()) => e -> LiftFOE (Throw e) f a
throw :: forall e a f. SendFOE (Throw e) f => e -> f a
throw' :: forall {k} (tag :: k) e a f. SendFOE (Tag (Throw e) tag) f => e -> f a
throw'' :: forall {k} (key :: k) e a f. SendFOEBy key (Throw e) f => e -> f a
catch :: forall a e f. SendHOE (Catch e) f => f a -> (e -> f a) -> f a
catch' :: forall {k} (tag :: k) a e f. SendHOE (TagH (Catch e) tag) f => f a -> (e -> f a) -> f a
catch'' :: forall {k} (key :: k) a e f. SendHOEBy key (Catch e) f => f a -> (e -> f a) -> f a
liftEither :: (Throw e <: f, Applicative f) => Either e a -> f a
joinEither :: (Throw e <: m, Monad m) => m (Either e a) -> m a
joinExcept :: Monad m => Either (m a) a -> m a
exc :: Monad m => m (Either (m a) a) -> m a
withExcept :: (Catch e <<: f, Throw e <: f, Applicative f) => f a -> (e -> f ()) -> f a
onExcept :: (Catch e <<: f, Throw e <: f, Applicative f) => f a -> f () -> f a

Documentation

data Throw e a where Source #

An effect to escape from the normal control structure with an exception value of type e in the middle of a context.

Constructors

Throw :: forall e a. e -> Throw e a

Throws an exception; that is, escapes from the normal control structure with an exception value in the middle of a context.

data Catch e (f :: Type -> Type) a where Source #

An effect to catch exceptions.

Constructors

Catch	Catches exceptions within a scope and processes them according to the given exception handler.
Fields :: forall (f :: Type -> Type) a e. f a The scope in which to catch exceptions. -> (e -> f a) Exception handler. Defines the processing to perform when an exception is thrown within the scope. -> Catch e f a

Instances

Instances details

() => HFunctor (Catch e) Source #
Instance details Defined in Data.Effect.Except Methods hfmap :: forall (f :: Type -> Type) (g :: Type -> Type). (f :-> g) -> Catch e f :-> Catch e g #

type LThrow e = LiftFOE (Throw e) Source #

pattern LThrow :: forall a e f a1. () => forall. (a ~ a1, ()) => e -> LiftFOE (Throw e) f a Source #

throw :: forall e a f. SendFOE (Throw e) f => e -> f a Source #

Throws an exception; that is, escapes from the normal control structure with an exception value in the middle of a context.

throw' :: forall {k} (tag :: k) e a f. SendFOE (Tag (Throw e) tag) f => e -> f a Source #

Throws an exception; that is, escapes from the normal control structure with an exception value in the middle of a context.

throw'' :: forall {k} (key :: k) e a f. SendFOEBy key (Throw e) f => e -> f a Source #

Throws an exception; that is, escapes from the normal control structure with an exception value in the middle of a context.

catch Source #

Arguments

:: forall a e f. SendHOE (Catch e) f
=> f a
-> (e -> f a)	Exception handler. Defines the processing to perform when an exception is thrown within the scope.
-> f a

Catches exceptions within a scope and processes them according to the given exception handler.

catch' Source #

Arguments

:: forall {k} (tag :: k) a e f. SendHOE (TagH (Catch e) tag) f
=> f a
-> (e -> f a)	Exception handler. Defines the processing to perform when an exception is thrown within the scope.
-> f a

Catches exceptions within a scope and processes them according to the given exception handler.

catch'' Source #

Arguments

:: forall {k} (key :: k) a e f. SendHOEBy key (Catch e) f
=> f a
-> (e -> f a)	Exception handler. Defines the processing to perform when an exception is thrown within the scope.
-> f a

Catches exceptions within a scope and processes them according to the given exception handler.

liftEither :: (Throw e <: f, Applicative f) => Either e a -> f a Source #

Throws the given Either value as an exception if it is Left.

joinEither :: (Throw e <: m, Monad m) => m (Either e a) -> m a Source #

Throws the result of the given action as an exception if it is Left.

joinExcept :: Monad m => Either (m a) a -> m a Source #

If the given Either value is Left, execute it as an action.

exc :: Monad m => m (Either (m a) a) -> m a Source #

If the result of the given action is Left, execute it as an action.

withExcept Source #

Arguments

:: (Catch e <<: f, Throw e <: f, Applicative f)
=> f a	Scope to which the exception handler applies
-> (e -> f ())	Exception handler
-> f a

If an exception occurs, executes the given exception handler, but the exception is not stopped there and is rethrown.

onExcept Source #

Arguments

:: (Catch e <<: f, Throw e <: f, Applicative f)
=> f a	Scope in which to detect exceptions
-> f ()	Action to execute in case of an exception
-> f a

If an exception occurs, executes the specified action, but the exception is not stopped there and is rethrown.