all() and race() implementations with effection v3 architecture

op-fns.ts

import type { Operation } from "./types.ts";
import { action, resource, spawn } from "./mod.ts";

export function all<T>(operations: Operation<T>[]): Operation<T[]> {
  return resource(function* All(provide) {
    let scope = yield* useScope();

    let tasks = operations.map(op => scope.run(() => op));

    let results = yield* map(tasks, task => task);

    yield* provide(results);
  });
}

export function race<T>(operations: Operation<T>[]): Operation<T> {
  return resource(function* Race(provide) {
    let scope = yield* useScope();
    
    let tasks = operations.map(op => scope.run(() => op));

    let winner = yield* action<T>(function*(resolve) {
      for (let task of tasks) {
        yield* spawn(function*() {
          resolve(yield* task);
        });
      }
    });

    // halt losers in parallel
    for (let task of tasks) {
      if (task !== winner) {
        yield* spawn(() => task.halt());
      }
    }

    yield* provide(winner);
  });
}

function* map<T, R>(values: T[], each: (value: T) => Operation<R>): Operation<R[]> {
  let results: R[] = [];

  for (let value of values) {
    results.push(yield* each(value));
  }

  return results;
}