Liminal Events beta

This portion of the documentation needs a rewrite.

Yield events from your conversation definition.

function* g() {
  yield* L.event("my-event")
}

When turning this definition into a strand, we can add an event handler.

await L.strand(g, {
  handler(event) {
    if (event === "my-event") {
      // ...
    }
  },
})

Extract Static Event Type

import { Definition, L } from "liminal"

function* g() {
  yield* L.emit("A")
  yield* L.emit(["B"])
  yield* L.emit({ c: "D" })
}

type GEvent = Definition.E<typeof g>

Custom Event Helper

Yielding plain string literals may not scale well. Instead, you can use EventBase to create custom event type factories and guards.

1. Create a unique symbol for your project

const CustomEventTag = Symbol.for("<your-project-name>/CustomEventTag")

2. Create the event constructor.

import { EventBase } from "liminal"

class MyEvent extends EventBase(YourProgramKey, "my_event") {}

3. Yield instances of the event from within your conversation definition.

function* g() {
  yield* L.event(new MyEvent())
}

4. Use the static is method of the custom event class.

await L.strand(
  function*() {
    yield* L.event(new AppEvent())
  },
  {
    handler(event) {
      if (MyEvent.is(event)) {
        // ...
      }
    },
  },
)