# eventium-core Changelog

## 0.2.0 (Unreleased)

See the [root changelog](../CHANGELOG.md) for full details.

### Breaking changes

- Record field prefixes removed from all core types. Fields accessed via
  `OverloadedRecordDot` (e.g. `projection.seed`, `event.metadata`).
  `NoFieldSelectors` and `DuplicateRecordFields` enabled as default extensions.
- `StreamEvent` now has 4 fields (added `EventMetadata`).
- `CommandHandler` gained an `err` type parameter; `commandHandlerHandler` renamed to `decide`.
- `ProcessManager` is now pure: `react` returns `[ProcessManagerEffect]`. `ProcessManagerEffect` only supports `IssueCommand` (removed `EmitEvent`).
- `EventPublisher`: removed `synchronousEventBusWrapper`; added `publishingEventStoreWriter` and `synchronousPublisher`.
- `PollingPeriodSeconds` (Double) replaced by `PollingIntervalMillis` (Int).
- Codec wrapper argument order changed (codec comes first).
- Removed `Eventium.ReadModel.Memory`.

### Internal

- Absorbed `x-sum-type-boilerplate` into `Eventium.TH.SumType`.
- Dropped `persistent-template` dependency.

### Additions

- `Eventium.TH.SumType` module: `constructSumType`, `sumTypeConverter`,
  `partialSumTypeConverter` (previously from `x-sum-type-boilerplate`).
- `NoFieldSelectors`, `DuplicateRecordFields`, `OverloadedRecordDot` default extensions.
- `EventMetadata`, `emptyMetadata`.
- `lenientCodecEventStoreReader`, `lenientCodecProjection`.
- `runProjectionSubscription`, `eventHandlerMapMaybe`.
- `CommandDispatcher` newtype with `mkCommandDispatcher` and `fireAndForgetDispatcher`.
- `CommandDispatchResult` (`CommandSucceeded` | `CommandFailed Text`).
- `IssueCommandWithCompensation` effect for saga compensation workflows.
- `processManagerEventHandler` for wiring a `ProcessManager` to an `EventHandler`.
- `Eventium.CommandDispatcher` module: `AggregateHandler`, `mkAggregateHandler`,
  `commandHandlerDispatcher` for list-based multi-aggregate command routing.
- `embeddedCommandHandler` returns `Right []` for non-matching commands
  (was `DecodeError` exception).

## 0.1.0

Initial release.