Scope resource for managing concurrency in effection

scope.ts

export interface ScopeOptions {
  maxConcurrency: number;
}

export interface Scope {
  (operation: Operation<T>): Operation<void>;
}
    
export function createScope(options: ScopeOptions): Operation<Scope> {
  let { maxConcurrency = Infinity } = options;
  let tasks = new Set<Task>();
  let buffer = [] as Task[];
  let queue = createQueue<Operation>;
  
  return {
    name: 'Scope',
    *init(scope) {
      yield spawn(queue.forEach(operation) {
        yield spawn(function*() {
          let task = yield spawn(operation);
          tasks.add(task);
          try {
            yield task;
          } finally {       
            tasks.delete(task);
            if (tasks.size() < maxConcurrency && buffer.length > 0) {
              queue.send(buffer.pop());
            }
        }, { scope });
      });
    
      return function* enqueue(operation) {
        if (tasks.size() < maxConcurrency) {
          queue.send(operation)
        } else {
          buffer.unshift(operation);
        }
      }
    }
  }
}