Control.Carrier.State.Church

A church-encoded carrier for the State effect.

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: 1.1.0.0

State carrier

runState :: forall s m a b. (s -> a -> m b) -> s -> StateC s m a -> m b

Run a State effect starting from the passed value, applying a continuation to the final state and result.

runState k s (pure a) = k s a

runState k s get = k s s

runState k s (put t) = k t ()

Since: 1.1.0.0

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

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

evalState = runState (const pure)

Since: 1.1.0.0

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

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

execState = runState (const . pure)

Since: 1.1.0.0

newtype StateC s (m :: Type -> Type) a

Since: 1.1.0.0

Constructors

StateC (forall r. (s -> a -> m r) -> s -> m r)

Instances

MonadTrans (StateC s)

Defined in Control.Carrier.State.Church

Methods

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

MonadIO m => MonadIO (StateC s m)

Defined in Control.Carrier.State.Church

Methods

liftIO :: IO a -> StateC s m a

Alternative m => Alternative (StateC s m)

Defined in Control.Carrier.State.Church

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]

Applicative (StateC s m)

Defined in Control.Carrier.State.Church

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

Functor (StateC s m)

Defined in Control.Carrier.State.Church

Methods

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

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

Monad (StateC s m)

Defined in Control.Carrier.State.Church

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

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

Defined in Control.Carrier.State.Church

Methods

mzero :: StateC s m a

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

MonadFail m => MonadFail (StateC s m)

Defined in Control.Carrier.State.Church

Methods

fail :: String -> StateC s m a

MonadFix m => MonadFix (StateC s m)

Defined in Control.Carrier.State.Church

Methods

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

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

Defined in Control.Carrier.State.Church

Methods

alg :: forall ctx (n :: Type -> Type) a. 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