| Safe Haskell | None |
|---|---|
| Language | Haskell2010 |
Eventful.Aggregate
Description
Defines an Aggregate type-class from DDD parlance.
- data Aggregate state event cmd = Aggregate {
- aggregateCommandHandler :: state -> cmd -> [event]
- aggregateProjection :: Projection state event
- allAggregateStates :: Aggregate state event cmd -> [cmd] -> [state]
- commandStoredAggregate :: Monad m => EventStore serialized m -> Aggregate state serialized cmd -> UUID -> cmd -> m [serialized]
Documentation
data Aggregate state event cmd Source #
An Aggregate is a combination of a Projection and a function to
validate commands against that Projection. When using an aggregate in some
service, it is common to simply load the latest projection state from the
event store and handle the command. If the command is valid then the new
events are applied to the projection in the event store.
Constructors
| Aggregate | |
Fields
| |
allAggregateStates :: Aggregate state event cmd -> [cmd] -> [state] Source #
Given a list commands, produce all of the states the aggregate's projection sees. This is useful for unit testing aggregates.
commandStoredAggregate :: Monad m => EventStore serialized m -> Aggregate state serialized cmd -> UUID -> cmd -> m [serialized] Source #
Loads the latest version of a Projection from the event store and tries to
apply the Aggregate command to it. If the command succeeds, then this
saves the events back to the store as well.