Control.Eff.Concurrent.Protocol.Observer

Observer Effects

This module supports the implementation of observers and observables. Expected use case is event propagation.

Since: 0.16.0

Documentation

data Observer o where

Describes a process that observes another via Asynchronous Pdu messages.

An observer consists of a filter and a process id. The filter converts an observation to a message understood by the observer process, and the ProcessId is used to send the message.

Since: 0.16.0

Constructors

Observer :: (Tangible o, TangiblePdu p Asynchronous, Tangible (Endpoint p), Typeable p) => (o -> Maybe (Pdu p Asynchronous)) -> Endpoint p -> Observer o

Instances

Eq (Observer o)

Defined in Control.Eff.Concurrent.Protocol.Observer

Methods

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

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

Ord (Observer o)

Defined in Control.Eff.Concurrent.Protocol.Observer

Methods

compare :: Observer o -> Observer o -> Ordering

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

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

(>) :: Observer o -> Observer o -> Bool

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

max :: Observer o -> Observer o -> Observer o

min :: Observer o -> Observer o -> Observer o

Show (Observer o)

Defined in Control.Eff.Concurrent.Protocol.Observer

Methods

showsPrec :: Int -> Observer o -> ShowS

show :: Observer o -> String

showList :: [Observer o] -> ShowS

NFData o => NFData (Observer o)

Defined in Control.Eff.Concurrent.Protocol.Observer

Methods

rnf :: Observer o -> ()

Show o => Show (Pdu (Observer o) r)

Defined in Control.Eff.Concurrent.Protocol.Observer

Methods

showsPrec :: Int -> Pdu (Observer o) r -> ShowS

show :: Pdu (Observer o) r -> String

showList :: [Pdu (Observer o) r] -> ShowS

NFData o => NFData (Pdu (Observer o) Asynchronous)

Defined in Control.Eff.Concurrent.Protocol.Observer

Methods

rnf :: Pdu (Observer o) Asynchronous -> ()

data Pdu (Observer o) r

A minimal Protocol for handling observations. This is one simple way of receiving observations - of course users can use any other Asynchronous Pdu message type for receiving observations.

Since: 0.16.0

Defined in Control.Eff.Concurrent.Protocol.Observer

data Pdu (Observer o) r where

• Observed :: forall o (r :: Synchronicity). o -> Pdu (Observer o) Asynchronous

type ToPretty (Observer o :: Type)

Defined in Control.Eff.Concurrent.Protocol.Observer

type ToPretty (Observer o :: Type) = PrettyParens ("observing" <:> ToPretty o)

type TangibleObserver o = (Tangible o, TangiblePdu (Observer o) Asynchronous)

The constraints on the type parameters to an Observer

Since: 0.24.0

data family Pdu (protocol :: Type) (reply :: Synchronicity)

This data family defines the **protocol data units**(PDU) of a protocol.

A Protocol in the sense of a communication interface description between processes.

The first parameter is usually a user defined type that identifies the protocol that uses the Pdus are. It maybe a phantom type.

The second parameter specifies if a specific constructor of an (GADT-like) Pdu instance is Synchronous, i.e. returns a result and blocks the caller or if it is Asynchronous

Example:

data BookShop deriving Typeable

data instance Pdu BookShop r where
  RentBook  :: BookId   -> Pdu BookShop ('Synchronous (Either RentalError RentalId))
  BringBack :: RentalId -> Pdu BookShop 'Asynchronous

type BookId = Int
type RentalId = Int
type RentalError = String

Instances

(Show (Pdu a1 r), Show (Pdu a2 r)) => Show (Pdu (a1, a2) r)

Defined in Control.Eff.Concurrent.Protocol

Methods

showsPrec :: Int -> Pdu (a1, a2) r -> ShowS

show :: Pdu (a1, a2) r -> String

showList :: [Pdu (a1, a2) r] -> ShowS

(Show (Pdu a1 r), Show (Pdu a2 r), Show (Pdu a3 r)) => Show (Pdu (a1, a2, a3) r)

Defined in Control.Eff.Concurrent.Protocol

Methods

showsPrec :: Int -> Pdu (a1, a2, a3) r -> ShowS

show :: Pdu (a1, a2, a3) r -> String

showList :: [Pdu (a1, a2, a3) r] -> ShowS

(Show (Pdu a1 r), Show (Pdu a2 r), Show (Pdu a3 r), Show (Pdu a4 r)) => Show (Pdu (a1, a2, a3, a4) r)

Defined in Control.Eff.Concurrent.Protocol

Methods

showsPrec :: Int -> Pdu (a1, a2, a3, a4) r -> ShowS

show :: Pdu (a1, a2, a3, a4) r -> String

showList :: [Pdu (a1, a2, a3, a4) r] -> ShowS

(Show (Pdu a1 r), Show (Pdu a2 r), Show (Pdu a3 r), Show (Pdu a4 r), Show (Pdu a5 r)) => Show (Pdu (a1, a2, a3, a4, a5) r)

Defined in Control.Eff.Concurrent.Protocol

Methods

showsPrec :: Int -> Pdu (a1, a2, a3, a4, a5) r -> ShowS

show :: Pdu (a1, a2, a3, a4, a5) r -> String

showList :: [Pdu (a1, a2, a3, a4, a5) r] -> ShowS

Show (ChildId p) => Show (Pdu (Sup p) (Synchronous r))

Defined in Control.Eff.Concurrent.Protocol.Supervisor

Methods

showsPrec :: Int -> Pdu (Sup p) (Synchronous r) -> ShowS

show :: Pdu (Sup p) (Synchronous r) -> String

showList :: [Pdu (Sup p) (Synchronous r)] -> ShowS

Show (Pdu (ObserverRegistry o) r)

Defined in Control.Eff.Concurrent.Protocol.Observer

Methods

showsPrec :: Int -> Pdu (ObserverRegistry o) r -> ShowS

show :: Pdu (ObserverRegistry o) r -> String

showList :: [Pdu (ObserverRegistry o) r] -> ShowS

Show o => Show (Pdu (Observer o) r)

Defined in Control.Eff.Concurrent.Protocol.Observer

Methods

showsPrec :: Int -> Pdu (Observer o) r -> ShowS

show :: Pdu (Observer o) r -> String

showList :: [Pdu (Observer o) r] -> ShowS

(NFData (Pdu a1 r), NFData (Pdu a2 r)) => NFData (Pdu (a1, a2) r)

Defined in Control.Eff.Concurrent.Protocol

Methods

rnf :: Pdu (a1, a2) r -> ()

(NFData (Pdu a1 r), NFData (Pdu a2 r), NFData (Pdu a3 r)) => NFData (Pdu (a1, a2, a3) r)

Defined in Control.Eff.Concurrent.Protocol

Methods

rnf :: Pdu (a1, a2, a3) r -> ()

(NFData (Pdu a1 r), NFData (Pdu a2 r), NFData (Pdu a3 r), NFData (Pdu a4 r)) => NFData (Pdu (a1, a2, a3, a4) r)

Defined in Control.Eff.Concurrent.Protocol

Methods

rnf :: Pdu (a1, a2, a3, a4) r -> ()

(NFData (Pdu a1 r), NFData (Pdu a2 r), NFData (Pdu a3 r), NFData (Pdu a4 r), NFData (Pdu a5 r)) => NFData (Pdu (a1, a2, a3, a4, a5) r)

Defined in Control.Eff.Concurrent.Protocol

Methods

rnf :: Pdu (a1, a2, a3, a4, a5) r -> ()

NFData (ChildId p) => NFData (Pdu (Sup p) (Synchronous r))

Defined in Control.Eff.Concurrent.Protocol.Supervisor

Methods

rnf :: Pdu (Sup p) (Synchronous r) -> ()

NFData (Pdu (ObserverRegistry o) r)

Defined in Control.Eff.Concurrent.Protocol.Observer

Methods

rnf :: Pdu (ObserverRegistry o) r -> ()

NFData o => NFData (Pdu (Observer o) Asynchronous)

Defined in Control.Eff.Concurrent.Protocol.Observer

Methods

rnf :: Pdu (Observer o) Asynchronous -> ()

data Pdu (Observer o) r

A minimal Protocol for handling observations. This is one simple way of receiving observations - of course users can use any other Asynchronous Pdu message type for receiving observations.

Since: 0.16.0

Defined in Control.Eff.Concurrent.Protocol.Observer

data Pdu (Observer o) r where

• Observed :: forall o (r :: Synchronicity). o -> Pdu (Observer o) Asynchronous

type ToPretty (Pdu x y :: Type)

Defined in Control.Eff.Concurrent.Protocol

type ToPretty (Pdu x y :: Type) = PrettySurrounded (PutStr "<") (PutStr ">") (("protocol" <:> ToPretty x) <+> ToPretty y)

data Pdu (a1, a2) x

Defined in Control.Eff.Concurrent.Protocol

data Pdu (a1, a2) x

• = ToPduLeft (Pdu a1 r)
• | ToPduRight (Pdu a2 r)

data Pdu (Sup p) r

The Pdu instance contains methods to start, stop and lookup a child process, as well as a diagnostic callback.

Since: 0.23.0

Defined in Control.Eff.Concurrent.Protocol.Supervisor

data Pdu (Sup p) r where

• StartC :: forall k (p :: k) (r :: Synchronicity) p. ChildId p -> Pdu (Sup p) (Synchronous (Either (SpawnErr p) (Endpoint (Protocol p))))
• StopC :: forall k (p :: k) (r :: Synchronicity) p. ChildId p -> Timeout -> Pdu (Sup p) (Synchronous Bool)
• LookupC :: forall k (p :: k) (r :: Synchronicity) p. ChildId p -> Pdu (Sup p) (Synchronous (Maybe (Endpoint (Protocol p))))
• GetDiagnosticInfo :: forall k (p :: k) (r :: Synchronicity). Pdu (Sup p) (Synchronous Text)

data Pdu (ObserverRegistry o) r

Protocol for managing observers. This can be added to any server for any number of different observation types. The functions manageObservers and handleObserverRegistration are used to include observer handling;

Since: 0.16.0

Defined in Control.Eff.Concurrent.Protocol.Observer

data Pdu (ObserverRegistry o) r where

• RegisterObserver :: forall k (o :: k) (r :: Synchronicity) o. NFData o => Observer o -> Pdu (ObserverRegistry o) Asynchronous
• ForgetObserver :: forall k (o :: k) (r :: Synchronicity) o. NFData o => Observer o -> Pdu (ObserverRegistry o) Asynchronous

data Pdu (a1, a2, a3) x

Defined in Control.Eff.Concurrent.Protocol

data Pdu (a1, a2, a3) x

• = ToPdu1 (Pdu a1 r)
• | ToPdu2 (Pdu a2 r)
• | ToPdu3 (Pdu a3 r)

data Pdu (a1, a2, a3, a4) x

Defined in Control.Eff.Concurrent.Protocol

data Pdu (a1, a2, a3, a4) x

• = ToPdu1Of4 (Pdu a1 r)
• | ToPdu2Of4 (Pdu a2 r)
• | ToPdu3Of4 (Pdu a3 r)
• | ToPdu4Of4 (Pdu a4 r)

data Pdu (a1, a2, a3, a4, a5) x

Defined in Control.Eff.Concurrent.Protocol

data Pdu (a1, a2, a3, a4, a5) x

• = ToPdu1Of5 (Pdu a1 r)
• | ToPdu2Of5 (Pdu a2 r)
• | ToPdu3Of5 (Pdu a3 r)
• | ToPdu4Of5 (Pdu a4 r)
• | ToPdu5Of5 (Pdu a5 r)

registerObserver :: (SetMember Process (Process q) r, HasCallStack, Member Interrupts r, TangibleObserver o, EmbedProtocol x (ObserverRegistry o), TangiblePdu x Asynchronous) => Observer o -> Endpoint x -> Eff r ()

And an Observer to the set of recipients for all observations reported by observed. Note that the observers are keyed by the observing process, i.e. a previous entry for the process contained in the Observer is overwritten. If you want multiple entries for a single process, just combine several filter functions.

Since: 0.16.0

forgetObserver :: (SetMember Process (Process q) r, HasCallStack, Member Interrupts r, Typeable o, NFData o, EmbedProtocol x (ObserverRegistry o), TangiblePdu x Asynchronous) => Observer o -> Endpoint x -> Eff r ()

Send the ForgetObserver message

Since: 0.16.0

handleObservations :: (HasCallStack, Typeable o, SetMember Process (Process q) r, NFData (Observer o)) => (o -> Eff r ()) -> Pdu (Observer o) Asynchronous -> Eff r ()

Based on the Pdu instance for Observer this simplified writing a callback handler for observations. In order to register to and ObserverRegistry use toObserver.

Since: 0.16.0

toObserver :: TangibleObserver o => Endpoint (Observer o) -> Observer o

Use a Endpoint as an Observer for handleObservations.

Since: 0.16.0

toObserverFor :: (TangibleObserver o, Typeable a, TangiblePdu a Asynchronous) => (o -> Pdu a Asynchronous) -> Endpoint a -> Observer o

Create an Observer that conditionally accepts all observations of the given type and applies the given function to them; the function takes an observation and returns an Pdu cast that the observer server is compatible to.

Since: 0.16.0

data ObserverRegistry o

A protocol for managing Observers, encompassing registration and de-registration of Observers.

Since: 0.16.0

Instances

Show (Pdu (ObserverRegistry o) r)

Defined in Control.Eff.Concurrent.Protocol.Observer

Methods

showsPrec :: Int -> Pdu (ObserverRegistry o) r -> ShowS

show :: Pdu (ObserverRegistry o) r -> String

showList :: [Pdu (ObserverRegistry o) r] -> ShowS

NFData (Pdu (ObserverRegistry o) r)

Defined in Control.Eff.Concurrent.Protocol.Observer

Methods

rnf :: Pdu (ObserverRegistry o) r -> ()

type ToPretty (ObserverRegistry o :: Type)

Defined in Control.Eff.Concurrent.Protocol.Observer

type ToPretty (ObserverRegistry o :: Type) = PrettyParens ("observer registry" <:> ToPretty o)

data Pdu (ObserverRegistry o) r

Protocol for managing observers. This can be added to any server for any number of different observation types. The functions manageObservers and handleObserverRegistration are used to include observer handling;

Since: 0.16.0

Defined in Control.Eff.Concurrent.Protocol.Observer

data Pdu (ObserverRegistry o) r where

• RegisterObserver :: forall k (o :: k) (r :: Synchronicity) o. NFData o => Observer o -> Pdu (ObserverRegistry o) Asynchronous
• ForgetObserver :: forall k (o :: k) (r :: Synchronicity) o. NFData o => Observer o -> Pdu (ObserverRegistry o) Asynchronous

type ObserverState o = State (Observers o)

Alias for the effect that contains the observers managed by manageObservers

data Observers o

Internal state for manageObservers

Instances

Eq (Observers o)

Defined in Control.Eff.Concurrent.Protocol.Observer

Methods

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

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

Ord (Observers o)

Defined in Control.Eff.Concurrent.Protocol.Observer

Methods

compare :: Observers o -> Observers o -> Ordering

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

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

(>) :: Observers o -> Observers o -> Bool

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

max :: Observers o -> Observers o -> Observers o

min :: Observers o -> Observers o -> Observers o

Show (Observers o)

Defined in Control.Eff.Concurrent.Protocol.Observer

Methods

showsPrec :: Int -> Observers o -> ShowS

show :: Observers o -> String

showList :: [Observers o] -> ShowS

NFData o => NFData (Observers o)

Defined in Control.Eff.Concurrent.Protocol.Observer

Methods

rnf :: Observers o -> ()

emptyObservers :: Observers o

The empty ObserverState

Since: 0.24.0

handleObserverRegistration :: forall o q r. (HasCallStack, Typeable o, SetMember Process (Process q) r, Member (ObserverState o) r, Member Logs r) => Pdu (ObserverRegistry o) Asynchronous -> Eff r ()

Provide the implementation for the ObserverRegistry Protocol, this handled RegisterObserver and ForgetObserver messages. It also adds the ObserverState constraint to the effect list.

Since: 0.16.0

manageObservers :: Eff (ObserverState o ': r) a -> Eff r a

Keep track of registered Observers.

Handle the ObserverState introduced by handleObserverRegistration.

Since: 0.16.0

observed :: forall o r q. (SetMember Process (Process q) r, Member (ObserverState o) r, Member Interrupts r, TangibleObserver o) => o -> Eff r ()

Report an observation to all observers. The process needs to manageObservers and to handleObserverRegistration.

Since: 0.16.0