Control.Object

Documentation

newtype Object e m

The type 'Object e m' represents objects which can handle messages e, perform actions in the environment m. It can be thought of as a function between effects. Thus, it can be composed just like functions using '(.>>.)' (not often needed); the identity element is echo.

Constructors

Object

Fields

runObject :: forall x. e x -> m (x, Object e m)

Instances

Typeable ((* -> *) -> (* -> *) -> *) Object

liftO :: Functor f => (forall x. e x -> f x) -> Object e f

Lift a natural transformation into an object.

transObject :: Functor g => (forall x. f x -> g x) -> Object e f -> Object e g

Change the workspace of the object.

adaptObject :: Functor m => (forall x. e x -> f x) -> Object f m -> Object e m

Apply a function to the messages coming into the object.

echo :: Functor e => Object e e

Parrots messages given.

(.>>.) :: Functor n => Object e m -> Object m n -> Object e n

Compose two objects (aka Dependency Injection).

oneshot :: (Functor e, Monad m) => (forall a. e (m a) -> m a) -> Object e m

Build an object.

stateful :: (Functor e, Monad m) => (forall a. e (StateT s m a) -> StateT s m a) -> s -> Object (AccessT s e) m

Build a stateful object.

class Stateful s f | f -> s where

Like MonadState, but doesn't require Monad as a prerequisite.

Methods

get_ :: f s

put_ :: s -> f ()

Instances

Stateful s (AccessT s f)

data AccessT s f a

Inflicts external state accessibility to arbitrary effects.

Constructors

Get (s -> a)

Put s a

LiftAccessT (f a)

Instances

Stateful s (AccessT s f)

Functor f => Functor (AccessT s f)

Typeable (* -> (* -> *) -> * -> *) AccessT

variable :: Applicative f => s -> Object (AccessT s Zero) f

A mutable variable.