auto task1 = async::spawn(

[] { std::cout << "Task 1 executes asynchronously" << std::endl; });

auto task2 = async::spawn([]() -> int {

std::cout << "Task 2 executes in parallel with task 1" << std::endl;

return 42;

});

auto task3 = task2.then([](int value) -> int {

std::cout << "Task 3 executes after task 2, which returned " << value

<< std::endl;

return value * 3;

});

auto task4 = async::when_all(task1, task3);

auto task5 =

task4.then([](std::tuple<async::task<void>, async::task<int>> results) {

std::cout << "Task 5 executes after tasks 1 and 3. Task 3 returned "

<< std::get<1>(results).get() << std::endl;

});

task5.get();

std::cout << "Task 5 has completed" << std::endl;

async::parallel_invoke(

[] { std::cout << "This is executed in parallel..." << std::endl; },

[] { std::cout << "with this" << std::endl; });

async::parallel_for(async::irange(0, 5), [](int x) { std::cout << x; });

std::cout << std::endl;

int r = async::parallel_reduce({1, 2, 3, 4}, 0,

[](int x, int y) { return x + y; });

std::cout << "The sum of {1, 2, 3, 4} is " << r << std::endl;