Control.Eff.Concurrent.Observer

Observer Effects

This module supports the implementation of observers and observables. One more concrete perspective might be to understand observers as event listeners and observables as event sources. The tools in this module are tailored towards Api endpoints

Documentation

class (Typeable p, Observable o) => Observer p o where

An Api index that support observation of the another Api that is Observable.

Minimal complete definition

observationMessage

Methods

observationMessage :: Server o -> Observation o -> Api p Asynchronous

Wrap the Observation and the ProcessId (i.e. the Server) that caused the observation into a Api value that the Observable understands.

Instances

Observable o => Observer (CallbackObserver o) o

Methods

observationMessage :: Server o -> Observation o -> Api (CallbackObserver o) Asynchronous

class (Typeable o, Typeable (Observation o)) => Observable o where

An Api index that supports registration and de-registration of Observers.

Minimal complete definition

registerObserverMessage, forgetObserverMessage

Associated Types

data Observation o

Type of observations visible on this observable

Methods

registerObserverMessage :: SomeObserver o -> Api o Asynchronous

Return the Api value for the cast_ that registeres an observer

forgetObserverMessage :: SomeObserver o -> Api o Asynchronous

Return the Api value for the cast_ that de-registeres an observer

notifyObserver :: (Member Process r, Member MessagePassing r, Observable o, Observer p o, HasCallStack) => Server p -> Server o -> Observation o -> Eff r ()

Send an Observation to an Observer

registerObserver :: (Member Process r, Member MessagePassing r, Observable o, Observer p o, HasCallStack) => Server p -> Server o -> Eff r ()

Send the registerObserverMessage

forgetObserver :: (Member Process r, Member MessagePassing r, Observable o, Observer p o) => Server p -> Server o -> Eff r ()

Send the forgetObserverMessage

data SomeObserver o where

An existential wrapper around a Server of an Observer. Needed to support different types of observers to observe the same Observable in a general fashion.

Constructors

SomeObserver :: (Show (Server p), Typeable p, Observer p o) => Server p -> SomeObserver o

Instances

Eq (SomeObserver o)

Methods

(==) :: SomeObserver o -> SomeObserver o -> Bool

(/=) :: SomeObserver o -> SomeObserver o -> Bool

Ord (SomeObserver o)

Methods

compare :: SomeObserver o -> SomeObserver o -> Ordering

(<) :: SomeObserver o -> SomeObserver o -> Bool

(<=) :: SomeObserver o -> SomeObserver o -> Bool

(>) :: SomeObserver o -> SomeObserver o -> Bool

(>=) :: SomeObserver o -> SomeObserver o -> Bool

max :: SomeObserver o -> SomeObserver o -> SomeObserver o

min :: SomeObserver o -> SomeObserver o -> SomeObserver o

Show (SomeObserver o)

Methods

showsPrec :: Int -> SomeObserver o -> ShowS

show :: SomeObserver o -> String

showList :: [SomeObserver o] -> ShowS

notifySomeObserver :: (Member Process r, Member MessagePassing r, Observable o, HasCallStack) => Server o -> Observation o -> SomeObserver o -> Eff r ()

Send an Observation to SomeObserver.

data Observers o

Internal state for manageobservers

manageObservers :: Eff (State (Observers o) ': r) a -> Eff r a

Keep track of registered Observers Observers can be added and removed, and an Observation can be sent to all registerd observers at once.

addObserver :: (Member MessagePassing r, Member (State (Observers o)) r, Observable o) => SomeObserver o -> Eff r ()

Add an Observer to the Observers managed by manageObservers.

removeObserver :: (Member MessagePassing r, Member (State (Observers o)) r, Observable o) => SomeObserver o -> Eff r ()

Delete an Observer from the Observers managed by manageObservers.

notifyObservers :: forall o r. (Observable o, Member MessagePassing r, Member Process r, Member (State (Observers o)) r) => Observation o -> Eff r ()

Send an Observation to all SomeObservers in the Observers state.

data CallbackObserver o

An Observer that dispatches the observations to an effectful callback.

Instances

Observable o => Observer (CallbackObserver o) o

Methods

observationMessage :: Server o -> Observation o -> Api (CallbackObserver o) Asynchronous

Show (Observation o) => Show (Api (CallbackObserver o) r)

Methods

showsPrec :: Int -> Api (CallbackObserver o) r -> ShowS

show :: Api (CallbackObserver o) r -> String

showList :: [Api (CallbackObserver o) r] -> ShowS

data Api (CallbackObserver o)

data Api (CallbackObserver o) where

• CbObserved :: Api (CallbackObserver o) Asynchronous

spawnCallbackObserver :: forall o r. (HasDispatcherIO r, Typeable o, Show (Observation o), Observable o) => (Server o -> Observation o -> Eff ProcIO Bool) -> Eff r (Server (CallbackObserver o))

Start a new process for an Observer that dispatches all observations to an effectful callback.