Effect CommunityEC
Effect Community•2y ago
danielo515

Interoperability of Long-Lived Effect Programs

Hello folks. As I convert more and more parts of my code into Effect, the confusion around interoperability is increasing.
Particularly about long-lived Effect programs and it's interactions with third party code that may also be long lived, but not for the entire life of the application.

The things that I think need a long-lived effect program are:
- Caching and batching of requests using requests resolvers
- Repetitive schedules, for example, repeat a task every minute
- Effects that subscribe to events coming from third party code like Svelte stores

The doubts that I have around it are:
- How I am supposed to run them? I don't have any particular runtime requirements, so up until now I just have been using Effect.runPromise(program). Does this promise need to be awaited in order to run?
- How can I properly teardown those programs ? For example, when the Svelte component gets destroyed. Someone suggested that maybe just providing an abort signal to runPromise may work, so I am doing this. Please see the piece of code attached and let me know if it makes sense

const me = writable(null as Me | null);

function init() {
  const run = Effect.gen(function* (_) {
    const meData = yield* fetchMe;
    if (meData !== undefined) me.set(meData);
  });
  const signal = new AbortController();
  Effect.runPromise(run, { signal: signal.signal });
  return () => ({
    destroy: () => signal.abort();
  });
}
export const appContext = { me, init }
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