Control.Carrier.State.Strict

A carrier for the State effect. It evaluates its inner state strictly, which is the correct choice for the majority of use cases.

Note that the parameter order in runState, evalState, and execState is reversed compared the equivalent functions provided by transformers. This is an intentional decision made to enable the composition of effect handlers with . without invoking flip.

Since: 1.0.0.0

Strict state carrier

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

Run a State effect starting from the passed value.

runState s (pure a) = pure (s, a)

runState s get = pure (s, s)

runState s (put t) = pure (t, ())

Since: 1.0.0.0

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

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

evalState s m = fmap snd (runState s m)

Since: 1.0.0.0

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

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

execState s m = fmap fst (runState s m)

Since: 1.0.0.0

newtype StateC s m a

Since: 1.0.0.0

Constructors

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

Instances

MonadTrans (StateC s)

Defined in Control.Carrier.State.Strict

Methods

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

Monad m => Monad (StateC s m)

Defined in Control.Carrier.State.Strict

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.Carrier.State.Strict

Methods

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

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

MonadFix m => MonadFix (StateC s m)

Defined in Control.Carrier.State.Strict

Methods

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

MonadFail m => MonadFail (StateC s m)

Defined in Control.Carrier.State.Strict

Methods

fail :: String -> StateC s m a

Monad m => Applicative (StateC s m)

Defined in Control.Carrier.State.Strict

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.Carrier.State.Strict

Methods

liftIO :: IO a -> StateC s m a

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

Defined in Control.Carrier.State.Strict

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.Carrier.State.Strict

Methods

mzero :: StateC s m a

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

Algebra sig m => Algebra (State s :+: sig) (StateC s m)

Defined in Control.Carrier.State.Strict

Methods

alg :: Functor ctx => Handler ctx n (StateC s m) -> (State s :+: sig) n a -> ctx () -> StateC s m (ctx a)

State effect

module Control.Effect.State