Observe.Event.Backend.Data

This module provides the DataEventBackend EventBackend for consuming events by representing them as ordinary Haskell data.

Documentation

newDataEventBackend :: forall m selector. (PrimMonad m, ParametricFunctor m) => m (DataEventBackend m selector)

Allocate a new DataEventBackend

getEvents :: PrimMonad m => DataEventBackend m selector -> m (Seq (Maybe (DataEvent selector)))

Read the events that have been emitted using the DataEventBackend

A Nothing indicates an event that hasn't been finalized.

data DataEvent selector

A representation of an event.

Constructors

forall f. DataEvent

Fields

• idx :: !Int

  This event's index in the sequence of event creations.

• selectors :: !(Selectors selector f)

  The selector used to initialize the event

• parent :: !(Maybe (Either Int (DataEvent selector)))

  The parent of this DataEvent, if any.

  Left n means the parent was the n'th event but wasn't finalized.

• causes :: ![Either Int (DataEvent selector)]

  The causes of this DataEvent.

  Left n means the cause was the n'th event but wasn't finalized.

• err :: !(Maybe SomeException)

  The error which ended the event, if any

• fields :: !(Seq f)

  The fields which were added to the event

• instant :: !Bool

  Whether the event was emitted instantly.

data Selectors selector field where

A nested sequence of selectors, starting from a given root selector family and ending in a selector selecting a given field type.

For example, given:

data FooSelector :: Type -> Type where Foo :: FooSelector FooField
data FooField
type instance SubSelector FooField = BarSelector
data BarSelector :: Type -> Type where Bar :: BarSelector BarField
data BarField
type instance SubSelector BarField = NoEventsSelector

Then Leaf Foo is a sequence Selectors picking out an Event with field type FooField, and Foo :/ Leaf Bar is a sequence of Selectors picking out an Event with field type BarField underneath an Event with field type FooField.

See the selector and field documentation for more details.

Constructors

Leaf :: selector field -> Selectors selector field

(:/) :: selector field -> Selectors (SubSelector field) field' -> Selectors selector field' infixr 5

data DataEventBackend m selector

An EventBackend for consuming events by representing them as ordinary Haskell data.

Create a new one with newDataEventBackend. Get the event data with getEvents.

Instances

(PrimMonad m, ParametricFunctor m) => EventBackendIn m (DataEventBackend m selector)

Consume events by representing them as ordinary Haskell data.

Defined in Observe.Event.Backend.Data

Methods

newEvent :: DataEventBackend m selector -> EventParams (RootSelector (DataEventBackend m selector)) field (EventReference (BackendEvent (DataEventBackend m selector))) -> m (BackendEvent (DataEventBackend m selector) field)

newInstantEvent :: DataEventBackend m selector -> EventParams (RootSelector (DataEventBackend m selector)) field (EventReference (BackendEvent (DataEventBackend m selector))) -> m (EventReference (BackendEvent (DataEventBackend m selector)))

EventBackend (DataEventBackend m selector)

Consume events by representing them as ordinary Haskell data.

Defined in Observe.Event.Backend.Data

Associated Types

type BackendEvent (DataEventBackend m selector) :: Type -> Type

type RootSelector (DataEventBackend m selector) :: Type -> Type

type BackendEvent (DataEventBackend m selector)

Defined in Observe.Event.Backend.Data

type BackendEvent (DataEventBackend m selector)

type RootSelector (DataEventBackend m selector)

Defined in Observe.Event.Backend.Data

type RootSelector (DataEventBackend m selector) = selector