Control.Effect.State.Lazy

Documentation

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

Constructors

Get (s -> k)

Put s k

Instances

Effect (State s)

Defined in Control.Effect.State.Internal

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.Internal

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.Internal

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.Strict

Methods

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

ret :: 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) (StateC s m a) -> StateC s m a

ret :: 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) => (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.

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

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

Replace the state value with the result of applying a function to the current state value. This is lazy in the new state; injudicious use of this function may lead to space leaks.

newtype StateC s m a

Constructors

StateC

Fields

• runStateC :: s -> m (s, a)

Instances

MonadTrans (StateC s)

Defined in Control.Effect.State.Lazy

Methods

lift :: Monad m => m a -> StateC s m a

Monad m => Monad (StateC s m)

Defined in Control.Effect.State.Lazy

Methods

(>>=) :: StateC s m a -> (a -> StateC s m b) -> StateC s m b

(>>) :: StateC s m a -> StateC s m b -> StateC s m b

return :: a -> StateC s m a

fail :: String -> StateC s m a

Functor m => Functor (StateC s m)

Defined in Control.Effect.State.Lazy

Methods

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

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

MonadFail m => MonadFail (StateC s m)

Defined in Control.Effect.State.Lazy

Methods

fail :: String -> StateC s m a

(Functor m, Monad m) => Applicative (StateC s m)

Defined in Control.Effect.State.Lazy

Methods

pure :: a -> StateC s m a

(<*>) :: StateC s m (a -> b) -> StateC s m a -> StateC s m b

liftA2 :: (a -> b -> c) -> StateC s m a -> StateC s m b -> StateC s m c

(*>) :: StateC s m a -> StateC s m b -> StateC s m b

(<*) :: StateC s m a -> StateC s m b -> StateC s m a

MonadIO m => MonadIO (StateC s m)

Defined in Control.Effect.State.Lazy

Methods

liftIO :: IO a -> StateC s m a

(Alternative m, Monad m) => Alternative (StateC s m)

Defined in Control.Effect.State.Lazy

Methods

empty :: StateC s m a

(<|>) :: StateC s m a -> StateC s m a -> StateC s m a

some :: StateC s m a -> StateC s m [a]

many :: StateC s m a -> StateC s m [a]

(Alternative m, Monad m) => MonadPlus (StateC s m)

Defined in Control.Effect.State.Lazy

Methods

mzero :: StateC s m a

mplus :: StateC s m a -> 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) (StateC s m a) -> StateC s m a

ret :: a -> StateC s m a

runState :: s -> StateC s m a -> m (s, a)

Run a lazy State effect, yielding the result value and the final state. More programs terminate with lazy state than strict state, but injudicious use of lazy state may lead to thunk buildup.

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

take 5 . snd . run $ runState () (traverse pure [1..]) == [1,2,3,4,5]

evalState :: forall s m a. Functor m => s -> StateC s m a -> m a

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

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

execState :: forall s m a. Functor m => s -> StateC s m a -> m s

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

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