Implement a restartable operation from any operation

use-restartable.ts

import {
  createChannel,
  each,
  Operation,
  resource,
  spawn,
  Task,
} from "effection";

export function useRestartable<TArgs extends unknown[]>(
  op: (...args: TArgs) => Operation<void>,
) {
  return resource<(...args: TArgs) => Operation<void>>(function* (provide) {
    let invocations = createChannel<TArgs, never>();

    let current: Task<void> | undefined = undefined;

    yield* spawn(function* () {
      for (let args of yield* each(invocations)) {
        if (current) {
          yield* current.halt();
        }
        current = yield* spawn(() => op(...args));
        yield* each.next();
      }
    });

    yield* provide(function* restart(...args) {
      yield* invocations.send(args);
    });
  });
}