Modulefused-effects-1.1.2.7Haskell2010

Control.Carrier.State.IORef

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 Control.Effect.NonDet effects.

1 type
4 values

Packagefused-effects-1.1.2.7
Exports5
LanguageHaskell2010
LicenceBSD-3-Clause
SourceIORef.hs

Impure state carrier

5 declarations

valuerunState :: MonadIO m => 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, ())

valuerunStateRef :: MonadIO m => IORef s -> StateC s m a -> m (s, a)

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

valueevalState :: MonadIO 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)

valueexecState :: MonadIO 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)

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

Constructors

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

Instances11MonadTrans, Monad, Functor, MonadFix, MonadFail, Applicative, …

MonadTrans (StateC s)Defined in fused-effects-1.1.2.7 · Control.Carrier.State.IORef
Monad m => Monad (StateC s m)Defined in fused-effects-1.1.2.7 · Control.Carrier.State.IORef
Functor m => Functor (StateC s m)Defined in fused-effects-1.1.2.7 · Control.Carrier.State.IORef
MonadFix m => MonadFix (StateC s m)Defined in fused-effects-1.1.2.7 · Control.Carrier.State.IORef
MonadFail m => MonadFail (StateC s m)Defined in fused-effects-1.1.2.7 · Control.Carrier.State.IORef
Applicative m => Applicative (StateC s m)Defined in fused-effects-1.1.2.7 · Control.Carrier.State.IORef
Alternative m => Alternative (StateC s m)Defined in fused-effects-1.1.2.7 · Control.Carrier.State.IORef
(Alternative m, Monad m) => MonadPlus (StateC s m)Defined in fused-effects-1.1.2.7 · Control.Carrier.State.IORef
MonadIO m => MonadIO (StateC s m)Defined in fused-effects-1.1.2.7 · Control.Carrier.State.IORef
MonadUnliftIO m => MonadUnliftIO (StateC s m)Defined in fused-effects-1.1.2.7 · Control.Carrier.State.IORef
(MonadIO m, Algebra sig m) => Algebra (State s :+: sig) (StateC s m)Defined in fused-effects-1.1.2.7 · Control.Carrier.State.IORef

State effect

0 declarations

module Control.Effect.State