Safe Haskell | None |
---|---|

Language | Haskell2010 |

## Synopsis

- data AtomicState s m a where
- AtomicState :: (s -> (s, a)) -> AtomicState s m a
- AtomicGet :: AtomicState s m s

- atomicState :: forall s a r. Member (AtomicState s) r => (s -> (s, a)) -> Sem r a
- atomicState' :: forall s a r. Member (AtomicState s) r => (s -> (s, a)) -> Sem r a
- atomicGet :: forall s r. Member (AtomicState s) r => Sem r s
- atomicPut :: Member (AtomicState s) r => s -> Sem r ()
- atomicModify :: Member (AtomicState s) r => (s -> s) -> Sem r ()
- atomicModify' :: Member (AtomicState s) r => (s -> s) -> Sem r ()
- runAtomicStateIORef :: forall s r a. Member (Embed IO) r => IORef s -> Sem (AtomicState s ': r) a -> Sem r a
- runAtomicStateTVar :: Member (Embed IO) r => TVar s -> Sem (AtomicState s ': r) a -> Sem r a
- atomicStateToIO :: forall s r a. Member (Embed IO) r => s -> Sem (AtomicState s ': r) a -> Sem r (s, a)
- atomicStateToState :: Member (State s) r => Sem (AtomicState s ': r) a -> Sem r a

# Effect

data AtomicState s m a where Source #

A variant of `State`

that supports atomic operations.

*Since: 1.1.0.0*

AtomicState :: (s -> (s, a)) -> AtomicState s m a | |

AtomicGet :: AtomicState s m s |

## Instances

type DefiningModule (AtomicState :: Type -> k -> Type -> Type) Source # | |

Defined in Polysemy.AtomicState |

# Actions

atomicState :: forall s a r. Member (AtomicState s) r => (s -> (s, a)) -> Sem r a Source #

Atomically reads and modifies the state.

atomicState' :: forall s a r. Member (AtomicState s) r => (s -> (s, a)) -> Sem r a Source #

A variant of `atomicState`

in which the computation is strict in the new
state and return value.

atomicModify :: Member (AtomicState s) r => (s -> s) -> Sem r () Source #

atomicModify' :: Member (AtomicState s) r => (s -> s) -> Sem r () Source #

A variant of `atomicModify`

in which the computation is strict in the
new state.

# Interpretations

runAtomicStateIORef :: forall s r a. Member (Embed IO) r => IORef s -> Sem (AtomicState s ': r) a -> Sem r a Source #

Run an `AtomicState`

effect by transforming it into atomic operations
over an `IORef`

.

runAtomicStateTVar :: Member (Embed IO) r => TVar s -> Sem (AtomicState s ': r) a -> Sem r a Source #

Run an `AtomicState`

effect by transforming it into atomic operations
over a `TVar`

.

atomicStateToIO :: forall s r a. Member (Embed IO) r => s -> Sem (AtomicState s ': r) a -> Sem r (s, a) Source #

Run an `AtomicState`

effect in terms of atomic operations
in `IO`

.

Internally, this simply creates a new `IORef`

, passes it to
`runAtomicStateIORef`

, and then returns the result and the final value
of the `IORef`

.

*Beware*: As this uses an `IORef`

internally,
all other effects will have local
state semantics in regards to `AtomicState`

effects
interpreted this way.
For example, `throw`

and `catch`

will
never revert `atomicModify`

s, even if `runError`

is used
after `atomicStateToIO`

.

*Since: 1.2.0.0*

atomicStateToState :: Member (State s) r => Sem (AtomicState s ': r) a -> Sem r a Source #

Transform an `AtomicState`

effect to a `State`

effect, discarding
the notion of atomicity.