Safe Haskell	Safe-Inferred
Language	Haskell2010

Control.Carrier.State.IORef

Contents

Impure state carrier
State effect

Description

A carrier for the State effect. It uses an IORef internally to handle its state, and thus admits a MonadUnliftIO instance. Because the state operations are performed impurely, this carrier will not lose state effects even with nefarious uses of liftWith.

Unlike the other carriers for State, this carrier's effects will not backtrack when run in conjuction with NonDet effects.

Since: 1.1.2.0

Synopsis

runState :: MonadIO m => s -> StateC s m a -> m (s, a)
runStateRef :: MonadIO m => IORef s -> StateC s m a -> m (s, a)
evalState :: forall s m a. MonadIO m => s -> StateC s m a -> m a
execState :: forall s m a. MonadIO m => s -> StateC s m a -> m s
newtype StateC s m a = StateC {
- runStateC :: ReaderC (IORef s) m a
}
module Control.Effect.State

Impure state carrier

runState :: MonadIO m => s -> StateC s m a -> m (s, a) Source #

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: 1.1.2.0

runStateRef :: MonadIO m => IORef s -> StateC s m a -> m (s, a) Source #

Run a State effect starting from the passed IORef. This function is lawless, given that the underlying IORef can be modified by another thread.

Since: 1.1.2.0

evalState :: forall s m a. MonadIO m => s -> StateC s m a -> m a Source #

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

evalState s m = fmap snd (runState s m)

Since: 1.1.2.0

execState :: forall s m a. MonadIO m => s -> StateC s m a -> m s Source #

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

execState s m = fmap fst (runState s m)

Since: 1.1.2.0

newtype StateC s m a Source #

Since: 1.1.2.0

Constructors

StateC
Fields runStateC :: ReaderC (IORef s) m a

Instances

Instances details

MonadTrans (StateC s) Source #
Instance details Defined in Control.Carrier.State.IORef Methods lift :: Monad m => m a -> StateC s m a #
MonadFail m => MonadFail (StateC s m) Source #
Instance details Defined in Control.Carrier.State.IORef Methods fail :: String -> StateC s m a #
MonadFix m => MonadFix (StateC s m) Source #
Instance details Defined in Control.Carrier.State.IORef Methods mfix :: (a -> StateC s m a) -> StateC s m a #
MonadIO m => MonadIO (StateC s m) Source #
Instance details Defined in Control.Carrier.State.IORef Methods liftIO :: IO a -> StateC s m a #
Alternative m => Alternative (StateC s m) Source #
Instance details Defined in Control.Carrier.State.IORef 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 m => Applicative (StateC s m) Source #
Instance details Defined in Control.Carrier.State.IORef 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 m => Functor (StateC s m) Source #
Instance details Defined in Control.Carrier.State.IORef Methods fmap :: (a -> b) -> StateC s m a -> StateC s m b # (<$) :: a -> StateC s m b -> StateC s m a #
Monad m => Monad (StateC s m) Source #
Instance details Defined in Control.Carrier.State.IORef 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) Source #
Instance details Defined in Control.Carrier.State.IORef Methods mzero :: StateC s m a # mplus :: StateC s m a -> StateC s m a -> StateC s m a #
MonadUnliftIO m => MonadUnliftIO (StateC s m) Source #
Instance details Defined in Control.Carrier.State.IORef Methods withRunInIO :: ((forall a. StateC s m a -> IO a) -> IO b) -> StateC s m b #
(MonadIO m, Algebra sig m) => Algebra (State s :+: sig) (StateC s m) Source #
Instance details Defined in Control.Carrier.State.IORef 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) Source #

State effect

module Control.Effect.State