// pack a lambda expression that returns 7 into a std::packaged_task

std::packaged_task<int()> task([](){return 7;});

// get the future of task

std::future<int> result = task.get_future(); // run task in a thread

std::thread(std::move(task)).detach();

std::cout << "waiting...";

result.wait(); // block until future has arrived

// output result

std::cout << "done!" << std:: endl << "future result is " << result.get() << std::endl;

return 0;

}