automata/event

Types

Event

An immutable record describing “something happened”.

body is a type parameter so callers can pipeline typed events (Event(MyDomainBody)) while ecosystem-wide layers can use the BuiltinEvent alias backed by automata/event/builtin/body.EventBody.

pub type Event(body) {
  Event(
    id: String,
    occurred_at: ast.ValidDateTime,
    source: source.Source,
    body: body,
    metadata: metadata.Metadata,
  )
}

Constructors

Event(
  id: String,
  occurred_at: ast.ValidDateTime,
  source: source.Source,
  body: body,
  metadata: metadata.Metadata,
)

Values

continue_from

</>

pub fn continue_from(
  parent parent: Event(parent_body),
  id id: String,
  occurred_at occurred_at: ast.ValidDateTime,
  source source: source.Source,
  body body: body,
) -> Event(body)

Derive a new event whose metadata chains from parent.

Inherits the parent’s correlation_id, trace_id, and the full attributes dict, and sets causation_id to parent.id. Use this when one event triggers another so the chain of custody — and any attributes that describe the chain itself (tenant, user, request id, etc.) — is preserved without manual bookkeeping. Reach for event.new plus with_metadata(metadata.empty()) when the child should start with a fresh attribute set; the inherited identifiers are the same value the parent had, so the child can always rebuild them explicitly when needed.

new

</>

pub fn new(
  id id: String,
  occurred_at occurred_at: ast.ValidDateTime,
  source source: source.Source,
  body body: body,
) -> Event(body)

Construct an event with empty metadata.

The caller supplies id. The library does not generate identifiers; pick a strategy (UUIDv7 / ULID / monotonic counter) that fits your transport.

with_attribute

</>

pub fn with_attribute(
  event event: Event(body),
  key key: String,
  value value: String,
) -> Event(body)

with_causation_id

</>

pub fn with_causation_id(
  event event: Event(body),
  id id: String,
) -> Event(body)

with_correlation_id

</>

pub fn with_correlation_id(
  event event: Event(body),
  id id: String,
) -> Event(body)

with_metadata

</>

pub fn with_metadata(
  event event: Event(body),
  metadata meta: metadata.Metadata,
) -> Event(body)

with_trace_id

</>

pub fn with_trace_id(
  event event: Event(body),
  id id: String,
) -> Event(body)