Copyright	(c) Fumiaki Kinoshita 2015
License	BSD3
Maintainer	Fumiaki Kinoshita <fumiexcel@gmail.com>
Stability	provisional
Portability	GADTs, Rank2Types
Safe Haskell	Safe
Language	Haskell2010

Control.Object.Object

Contents

Description

Synopsis

newtype Object f g = Object {
- runObject :: forall x. f x -> g (x, Object f g)
}
echo :: Functor f => Object f f
(@>>@) :: Functor h => Object f g -> Object g h -> Object f h
(@<<@) :: Functor h => Object g h -> Object f g -> Object f h
liftO :: Functor g => (forall x. f x -> g x) -> Object f g
(^>>@) :: Functor h => (forall x. f x -> g x) -> Object g h -> Object f h
(@>>^) :: Functor h => Object f g -> (forall x. g x -> h x) -> Object f h
(@||@) :: Functor h => Object f h -> Object g h -> Object (f `Sum` g) h
unfoldO :: Functor g => (forall a. r -> f a -> g (a, r)) -> r -> Object f g
stateful :: Monad m => (forall a. t a -> StateT s m a) -> s -> Object t m
(@~) :: Monad m => s -> (forall a. t a -> StateT s m a) -> Object t m
variable :: Monad m => s -> Object (StateT s m) m
(@-) :: Object f g -> f x -> g (x, Object f g)
cascadeObject :: Monad m => Object t m -> Skeleton t a -> m (a, Object t m)
cascading :: Monad m => Object t m -> Object (Skeleton t) m
data Fallible t a where
- Fallible :: t a -> Fallible t (Maybe a)
filteredO :: Monad m => (forall x. t x -> Bool) -> Object t m -> Object (Fallible t) m
filterO :: (forall x. t x -> Bool) -> Object (Fallible t) (Skeleton t)
invokesOf :: Monad m => ((Object t m -> WriterT r m (Object t m)) -> s -> WriterT r m s) -> t a -> (a -> r) -> StateT s m r
invokes :: (Traversable t, Monad m, Monoid r) => f a -> (a -> r) -> StateT (t (Object f m)) m r
(@!=) :: Monad m => ((Object t m -> WriterT a m (Object t m)) -> s -> WriterT a m s) -> t a -> StateT s m a
announce :: (Traversable t, Monad m) => f a -> StateT (t (Object f m)) m [a]

Documentation

newtype Object f g Source #

The type Object f g represents objects which can handle messages f, perform actions in the environment g. It can be thought of as an automaton that transforms effects. Objects can be composed just like functions using @>>@; the identity element is echo. Objects are morphisms of the category of actions.

Naturality: runObject obj . fmap f ≡ fmap f . runObject obj

Constructors

Object
Fields runObject :: forall x. f x -> g (x, Object f g)

echo :: Functor f => Object f f Source #

The trivial object

(@>>@) :: Functor h => Object f g -> Object g h -> Object f h infixr 1 Source #

The categorical composition of objects.

(@<<@) :: Functor h => Object g h -> Object f g -> Object f h infixl 1 Source #

Reversed (@>>@)

liftO :: Functor g => (forall x. f x -> g x) -> Object f g Source #

Lift a natural transformation into an object.

(^>>@) :: Functor h => (forall x. f x -> g x) -> Object g h -> Object f h infixr 1 Source #

(@>>^) :: Functor h => Object f g -> (forall x. g x -> h x) -> Object f h infixr 1 Source #

(@||@) :: Functor h => Object f h -> Object g h -> Object (f `Sum` g) h Source #

Combine objects so as to handle a Sum of interfaces.

Stateful construction

unfoldO :: Functor g => (forall a. r -> f a -> g (a, r)) -> r -> Object f g Source #

An unwrapped analog of stateful id = unfoldO runObject iterative = unfoldO iterObject cascading = unfoldO cascadeObject

stateful :: Monad m => (forall a. t a -> StateT s m a) -> s -> Object t m Source #

Build a stateful object.

stateful t s = t ^>>@ variable s

(@~) :: Monad m => s -> (forall a. t a -> StateT s m a) -> Object t m infix 1 Source #

Flipped stateful. it is super convenient to use with the LambdaCase extension.

variable :: Monad m => s -> Object (StateT s m) m Source #

A mutable variable.

variable = stateful id

Method cascading

(@-) :: Object f g -> f x -> g (x, Object f g) infixr 3 Source #

An infix alias for runObject

cascadeObject :: Monad m => Object t m -> Skeleton t a -> m (a, Object t m) Source #

Pass zero or more messages to an object.

cascading :: Monad m => Object t m -> Object (Skeleton t) m Source #

Add capability to handle multiple messages at once.

Filtering

data Fallible t a where Source #

Constructors

Fallible :: t a -> Fallible t (Maybe a)

filteredO :: Monad m => (forall x. t x -> Bool) -> Object t m -> Object (Fallible t) m Source #

filterO :: (forall x. t x -> Bool) -> Object (Fallible t) (Skeleton t) Source #

Manipulation on StateT

invokesOf :: Monad m => ((Object t m -> WriterT r m (Object t m)) -> s -> WriterT r m s) -> t a -> (a -> r) -> StateT s m r Source #

Send a message to an object through a lens.

invokes :: (Traversable t, Monad m, Monoid r) => f a -> (a -> r) -> StateT (t (Object f m)) m r Source #

(@!=) :: Monad m => ((Object t m -> WriterT a m (Object t m)) -> s -> WriterT a m s) -> t a -> StateT s m a Source #

A method invocation operator on StateT.

announce :: (Traversable t, Monad m) => f a -> StateT (t (Object f m)) m [a] Source #

Send a message to objects in a traversable container.