Utility Helpers

Two helpers ship with @requence/service. Both exist for the same reason: a continuous generator has to stop when the task is stopped, and wiring ctx.terminated into every loop by hand is easy to forget.

TypeScript only

Both helpers are @requence/service exports. The Python SDK has no asyncio, so a Python generator checks ctx.terminated.is_set() in its own loop instead.

wrapIterable(iterable)

Wraps any Iterable or AsyncIterable so that iteration stops automatically when ctx.terminated resolves.

import { createService, wrapIterable } from '@requence/service'

createService('1.0.0', async function* (ctx) {
  for await (const event of wrapIterable(eventStream)) {
    yield processEvent(event)
  }
})

asyncEventEmitter(initial?)

Creates an async-iterable emitter that integrates with ctx.terminated. Push values in from outside — an event listener, a callback, a webhook — and iterate them inside the generator. The iterator exits by itself when the task is terminated.

import { asyncEventEmitter, createService } from '@requence/service'

createService('1.0.0', async function* (ctx) {
  const emitter = asyncEventEmitter<string>()

  externalSource.on('data', (value) => emitter.push(value))

  for await (const value of emitter) {
    yield { value }
  }
})

It is also the usual way to hold a act() actor open while it waits for a surface interaction.