Control.Effect.State

Documentation

data State s (m :: * -> *) k

Constructors

Get (s -> k)

Put s k

Instances

Effect (State s)

Defined in Control.Effect.State

Methods

handle :: Functor f => f () -> (forall x. f (m x) -> n (f x)) -> State s m (m a) -> State s n (n (f a))

HFunctor (State s)

Defined in Control.Effect.State

Methods

fmap' :: (a -> b) -> State s m a -> State s m b

hmap :: (forall x. m x -> n x) -> State s m a -> State s n a

Functor (State s m)

Defined in Control.Effect.State

Methods

fmap :: (a -> b) -> State s m a -> State s m b

(<$) :: a -> State s m b -> State s m a

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

Defined in Control.Effect.State

Methods

ret :: a -> StateC s m a

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

get :: (Member (State s) sig, Carrier sig m) => m s

Get the current state value.

snd (run (runState a get)) == a

gets :: (Member (State s) sig, Carrier sig m) => (s -> a) -> m a

Project a function out of the current state value.

snd (run (runState a (gets (applyFun f)))) == applyFun f a

put :: (Member (State s) sig, Carrier sig m) => s -> m ()

Replace the state value with a new value.

fst (run (runState a (put b))) == b

snd (run (runState a (get <* put b))) == a

snd (run (runState a (put b *> get))) == b

modify :: (Member (State s) sig, Carrier sig m, Monad m) => (s -> s) -> m ()

Replace the state value with the result of applying a function to the current state value. This is strict in the new state; if you need laziness, use get >>= put . f.

fst (run (runState a (modify (+1)))) == (1 + a :: Integer)

runState :: forall s sig m a. (Carrier sig m, Effect sig) => s -> Eff (StateC s m) a -> m (s, a)

Run a State effect starting from the passed value.

run (runState a (pure b)) == (a, b)

evalState :: forall s sig m a. (Carrier sig m, Effect sig, Functor m) => s -> Eff (StateC s m) a -> m a

Run a State effect, yielding the result value and discarding the final state.

run (evalState a (pure b)) == b

execState :: forall s sig m a. (Carrier sig m, Effect sig, Functor m) => s -> Eff (StateC s m) a -> m s

Run a State effect, yielding the final state and discarding the return value.

run (execState a (pure b)) == a

newtype StateC s m a

Constructors

StateC

Fields

• runStateC :: s -> m (s, a)

Instances

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

Defined in Control.Effect.State

Methods

ret :: a -> StateC s m a

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