Control.Carrier.Empty.Church

A church-encoded carrier for Empty.

Since: 1.1.0.0

Empty carrier

runEmpty :: m b -> (a -> m b) -> EmptyC m a -> m b

Run an Empty effect, returning the first continuation for empty programs and applying the second to successful results.

runEmpty j k empty = j

runEmpty j k (pure a) = k a

Since: 1.1.0.0

evalEmpty :: Applicative m => EmptyC m a -> m ()

Run an Empty effect, discarding its result.

This is convenient for using empty to signal early returns without needing to know whether control exited normally or not.

evalEmpty = runEmpty (pure ()) (const (pure ()))

Since: 1.1.0.0

execEmpty :: Applicative m => EmptyC m a -> m Bool

Run an Empty effect, replacing its result with a Bool indicating whether control exited normally.

This is convenient for using empty to signal early returns when all you need to know is whether control exited normally or not, and not what value it exited with.

execEmpty = runEmpty (pure False) (const (pure True))

execEmpty (pure a) = pure True

execEmpty empty = pure False

Since: 1.1.0.0

newtype EmptyC (m :: Type -> Type) a

Since: 1.1.0.0

Constructors

EmptyC (forall b. m b -> (a -> m b) -> m b)

Instances

MonadTrans EmptyC

Defined in Control.Carrier.Empty.Church

Methods

lift :: Monad m => m a -> EmptyC m a

Applicative (EmptyC m)

Defined in Control.Carrier.Empty.Church

Methods

pure :: a -> EmptyC m a

(<*>) :: EmptyC m (a -> b) -> EmptyC m a -> EmptyC m b

liftA2 :: (a -> b -> c) -> EmptyC m a -> EmptyC m b -> EmptyC m c

(*>) :: EmptyC m a -> EmptyC m b -> EmptyC m b

(<*) :: EmptyC m a -> EmptyC m b -> EmptyC m a

Functor (EmptyC m)

Defined in Control.Carrier.Empty.Church

Methods

fmap :: (a -> b) -> EmptyC m a -> EmptyC m b

(<$) :: a -> EmptyC m b -> EmptyC m a

Monad (EmptyC m)

Defined in Control.Carrier.Empty.Church

Methods

(>>=) :: EmptyC m a -> (a -> EmptyC m b) -> EmptyC m b

(>>) :: EmptyC m a -> EmptyC m b -> EmptyC m b

return :: a -> EmptyC m a

MonadFail m => MonadFail (EmptyC m)

Defined in Control.Carrier.Empty.Church

Methods

fail :: String -> EmptyC m a

MonadFix m => MonadFix (EmptyC m)

Defined in Control.Carrier.Empty.Church

Methods

mfix :: (a -> EmptyC m a) -> EmptyC m a

MonadIO m => MonadIO (EmptyC m)

Defined in Control.Carrier.Empty.Church

Methods

liftIO :: IO a -> EmptyC m a

Algebra sig m => Algebra (Empty :+: sig) (EmptyC m)

Defined in Control.Carrier.Empty.Church

Methods

alg :: forall ctx (n :: Type -> Type) a. Functor ctx => Handler ctx n (EmptyC m) -> (Empty :+: sig) n a -> ctx () -> EmptyC m (ctx a)

Empty effect

module Control.Effect.Empty