Control.Effect.Error

Error effect

data Error exc m k

Constructors

Throw exc

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

Instances

Effect (Error exc)

Defined in Control.Effect.Error

Methods

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

HFunctor (Error exc)

Defined in Control.Effect.Error

Methods

fmap' :: Functor (Error exc f) => (a -> b) -> Error exc f a -> Error exc f b

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

Functor m => 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) => Carrier (Error e :+: sig) (ErrorC e m)

Defined in Control.Effect.Error

Methods

eff :: (Error e :+: sig) (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). Note that this effect does not handle errors thrown from impure contexts such as IO, nor will it handle exceptions thrown from pure code. If you need to handle IO-based errors, consider if Resource fits your use case; if not, use liftIO with try or use Catch from outside the effect invocation.

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

Error carrier

runError :: 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

MonadTrans (ErrorC e)

Defined in Control.Effect.Error

Methods

lift :: Monad m => m a -> ErrorC e m a

Monad m => Monad (ErrorC e m)

Defined in Control.Effect.Error

Methods

(>>=) :: ErrorC e m a -> (a -> ErrorC e m b) -> ErrorC e m b

(>>) :: ErrorC e m a -> ErrorC e m b -> ErrorC e m b

return :: a -> ErrorC e m a

fail :: String -> ErrorC e m a

Functor m => Functor (ErrorC e m)

Defined in Control.Effect.Error

Methods

fmap :: (a -> b) -> ErrorC e m a -> ErrorC e m b

(<$) :: a -> ErrorC e m b -> ErrorC e m a

MonadFix m => MonadFix (ErrorC e m)

Defined in Control.Effect.Error

Methods

mfix :: (a -> ErrorC e m a) -> ErrorC e m a

MonadFail m => MonadFail (ErrorC e m)

Defined in Control.Effect.Error

Methods

fail :: String -> ErrorC e m a

Applicative m => Applicative (ErrorC e m)

Defined in Control.Effect.Error

Methods

pure :: a -> ErrorC e m a

(<*>) :: ErrorC e m (a -> b) -> ErrorC e m a -> ErrorC e m b

liftA2 :: (a -> b -> c) -> ErrorC e m a -> ErrorC e m b -> ErrorC e m c

(*>) :: ErrorC e m a -> ErrorC e m b -> ErrorC e m b

(<*) :: ErrorC e m a -> ErrorC e m b -> ErrorC e m a

MonadIO m => MonadIO (ErrorC e m)

Defined in Control.Effect.Error

Methods

liftIO :: IO a -> ErrorC e m a

Alternative m => Alternative (ErrorC e m)

Defined in Control.Effect.Error

Methods

empty :: ErrorC e m a

(<|>) :: ErrorC e m a -> ErrorC e m a -> ErrorC e m a

some :: ErrorC e m a -> ErrorC e m [a]

many :: ErrorC e m a -> ErrorC e m [a]

(Alternative m, Monad m) => MonadPlus (ErrorC e m)

Defined in Control.Effect.Error

Methods

mzero :: ErrorC e m a

mplus :: ErrorC e m a -> ErrorC e m a -> ErrorC e m a

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

Defined in Control.Effect.Error

Methods

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

Re-exports

class (HFunctor sig, Monad m) => Carrier sig m | m -> sig

The class of carriers (results) for algebras (effect handlers) over signatures (effects), whose actions are given by the eff method.

Minimal complete definition

eff

Instances

Carrier Pure PureC

Defined in Control.Effect.Carrier

Methods

eff :: Pure PureC a -> PureC a

(HFunctor eff, Carrier sig m, Member eff sig) => Carrier sig (InterposeC eff m)

Defined in Control.Effect.Interpose

Methods

eff :: sig (InterposeC eff m) a -> InterposeC eff m a

Monad m => Carrier (Lift m) (LiftC m)

Defined in Control.Effect.Lift

Methods

eff :: Lift m (LiftC m) a -> LiftC m a

(Carrier sig m, MonadIO m) => Carrier (Resource :+: sig) (ResourceC m)

Defined in Control.Effect.Resource

Methods

eff :: (Resource :+: sig) (ResourceC m) a -> ResourceC m a

(Carrier sig m, Effect sig) => Carrier (NonDet :+: sig) (NonDetC m)

Defined in Control.Effect.NonDet

Methods

eff :: (NonDet :+: sig) (NonDetC m) a -> NonDetC m a

(Carrier sig m, Effect sig) => Carrier (NonDet :+: sig) (OnceC m)

Defined in Control.Effect.Cull

Methods

eff :: (NonDet :+: sig) (OnceC m) a -> OnceC m a

(Carrier sig m, Effect sig) => Carrier (Fresh :+: sig) (FreshC m)

Defined in Control.Effect.Fresh

Methods

eff :: (Fresh :+: sig) (FreshC m) a -> FreshC m a

(Carrier sig m, Effect sig) => Carrier (Fail :+: sig) (FailC m)

Defined in Control.Effect.Fail

Methods

eff :: (Fail :+: sig) (FailC m) a -> FailC m a

(Carrier sig m, Effect sig) => Carrier (Cut :+: (NonDet :+: sig)) (CutC m)

Defined in Control.Effect.Cut

Methods

eff :: (Cut :+: (NonDet :+: sig)) (CutC m) a -> CutC m a

(Carrier sig m, Effect sig) => Carrier (Cull :+: (NonDet :+: sig)) (CullC m)

Defined in Control.Effect.Cull

Methods

eff :: (Cull :+: (NonDet :+: sig)) (CullC m) a -> CullC m a

(Carrier sig m, Effect sig) => Carrier (Trace :+: sig) (TraceByReturningC m)

Defined in Control.Effect.Trace

Methods

eff :: (Trace :+: sig) (TraceByReturningC m) a -> TraceByReturningC m a

Carrier sig m => Carrier (Trace :+: sig) (TraceByIgnoringC m)

Defined in Control.Effect.Trace

Methods

eff :: (Trace :+: sig) (TraceByIgnoringC m) a -> TraceByIgnoringC m a

(MonadIO m, Carrier sig m) => Carrier (Trace :+: sig) (TraceByPrintingC m)

Defined in Control.Effect.Trace

Methods

eff :: (Trace :+: sig) (TraceByPrintingC m) a -> TraceByPrintingC m a

(HFunctor eff, Carrier sig m) => Carrier (eff :+: sig) (InterpretC eff m)

Defined in Control.Effect.Interpret

Methods

eff :: (eff :+: sig) (InterpretC eff m) a -> InterpretC eff m a

(Carrier sig m, Effect sig) => Carrier (State s :+: sig) (StateC s m)

Defined in Control.Effect.State.Strict

Methods

eff :: (State s :+: sig) (StateC s m) a -> StateC s m a

(Carrier sig m, Effect sig) => Carrier (State s :+: sig) (StateC s m)

Defined in Control.Effect.State.Lazy

Methods

eff :: (State s :+: sig) (StateC s m) a -> StateC s m a

Carrier sig m => Carrier (Reader r :+: sig) (ReaderC r m)

Defined in Control.Effect.Reader

Methods

eff :: (Reader r :+: sig) (ReaderC r m) a -> ReaderC r m a

(Carrier sig m, Effect sig, RandomGen g) => Carrier (Random :+: sig) (RandomC g m)

Defined in Control.Effect.Random

Methods

eff :: (Random :+: sig) (RandomC g m) a -> RandomC g m a

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

Defined in Control.Effect.Error

Methods

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

Carrier sig m => Carrier (Resumable err :+: sig) (ResumableWithC err m)

Defined in Control.Effect.Resumable

Methods

eff :: (Resumable err :+: sig) (ResumableWithC err m) a -> ResumableWithC err m a

(Carrier sig m, Effect sig) => Carrier (Resumable err :+: sig) (ResumableC err m)

Defined in Control.Effect.Resumable

Methods

eff :: (Resumable err :+: sig) (ResumableC err m) a -> ResumableC err m a

(Monoid w, Carrier sig m, Effect sig) => Carrier (Writer w :+: sig) (WriterC w m)

Defined in Control.Effect.Writer

Methods

eff :: (Writer w :+: sig) (WriterC w m) a -> WriterC w m a

(HFunctor eff, Carrier sig m, Effect sig) => Carrier (eff :+: sig) (InterpretStateC eff s m)

Defined in Control.Effect.Interpret

Methods

eff :: (eff :+: sig) (InterpretStateC eff s m) a -> InterpretStateC eff s m a

class Member (sub :: (* -> *) -> * -> *) sup

Minimal complete definition

inj, prj

Instances

Member sub sub

Defined in Control.Effect.Sum

Methods

inj :: sub m a -> sub m a

prj :: sub m a -> Maybe (sub m a)

Member sub sup => Member sub (sub' :+: sup)

Defined in Control.Effect.Sum

Methods

inj :: sub m a -> (sub' :+: sup) m a

prj :: (sub' :+: sup) m a -> Maybe (sub m a)

Member sub (sub :+: sup)

Defined in Control.Effect.Sum

Methods

inj :: sub m a -> (sub :+: sup) m a

prj :: (sub :+: sup) m a -> Maybe (sub m a)

run :: PureC a -> a

Run an action exhausted of effects to produce its final result value.