Revision history for servant-event-stream

0.4.0.0 -- 2026-02-27

• Breaking: Add eventComment and eventRetry fields to ServerEvent. Existing code using the ServerEvent constructor must add the new fields, e.g. ServerEvent typ eid dat Nothing Nothing.
• Breaking: Drop charset=utf-8 from the Accept instance. The content type is now text/event-stream (no parameters), matching the WHATWG spec.
• New dependency: aeson (for JSON helpers).
• New dependency: servant-client-core (for HasClient instances).
• Add serverEvent convenience constructor matching the old 3-field API for easy migration.
• Add dataEvent convenience constructor for simple data-only events.
• Add commentEvent convenience constructor for heartbeat keepalives.
• Add retryEvent convenience constructor for setting client reconnection delay.
• Export encodeServerEvent for direct use outside of Servant.
• Add FromServerEvent typeclass and decodeServerEvent for parsing SSE events.
• Add MimeUnrender EventStream and FramingUnrender ServerEventFraming instances for consuming SSE streams.
• Add HasClient instances for ServerSentEvents and PostServerSentEvents, enabling client-side SSE consumption via servant-client.
• Add PostServerSentEvents combinator for POST SSE endpoints (e.g. OpenAI's streaming API), with HasServer, HasClient, and HasForeign instances.
• Add JsonData newtype for deriving ToServerEvent and FromServerEvent via JSON encoding using DerivingVia.
• Add jsonEvent helper to construct events with JSON-encoded data payloads.
• Add jsonData helper to decode JSON from an event's data field.
• Strip leading UTF-8 BOM from SSE input, per the WHATWG spec.
• Export ServerEventFraming (needed for StreamPost SSE endpoints).
• Always emit at least one data: field, even when eventData is empty. Previously, empty data produced no output and the event was silently dropped by clients.
• Sanitize eventType, eventId, and eventComment by stripping CR and LF characters to prevent malformed SSE output.
• Strip NULL characters from eventId (the SSE spec silently ignores ids containing NULL).

0.3.2.1 -- 2026-02-27

• Add guard space after colon in SSE field encoding. Without it, field values starting with a space lost their leading space because the SSE spec strips exactly one leading space from field values. (Issue #16)
• Add unit tests for encodeServerEvent.

0.3.2.0 -- 2026-02-23

• Support GHC 8.6 through 9.12 (base 4.12 to 4.21).
• Remove redundant Typeable deriving to fix -Wderiving-typeable warning on GHC 9.12+.
• Add CI test matrix for GHC 8.6, 8.10, 9.2, 9.8, 9.12.

0.3.1.1 -- 2026-02-23

• Constrain base bounds in test suite to match library.

0.3.1.0 -- 2025-08-21

• Qualify servant imports so that ServerSentEvents added in servant-0.20.3.0 does not conflict with ours. (Issue #12)

0.3.0.0 -- 2024-09-05

• Breaking changes to the API.

  Event streams are implemented using servant's 'Stream' endpoint. You should provide a handler that returns a stream of events that implements 'ToSourceIO' where events have a 'ToServerEvent' instance.

  Example:

  type MyApi = "books" :> ServerSentEvents (SourceIO Book)

  instance ToServerEvent Book where toServerEvent book = ...

  server :: Server MyApi server = streamBooks where streamBooks :: Handler (SourceIO Book) streamBooks = pure $ source [book1, ...]

0.2.1.0 -- 2021-04-21

• Import Data.Semigroup for base < 4.11.0

0.2.0.0 -- 2021-04-20

• Servant.EventStream was moved to Servant.API.EventStream to adhere existing upstream layout.

0.1.0.0 -- 2018-04-30

• First version. Released on an unsuspecting world.