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I have a few questions about the implementation of the function then() in Herb Sutter's talk . This function is used to chain asynchronous operations, the parameter f is a future from one operation and the parameter w is the 'work' for this operation (lambda). template <typename Fut, typename Work> auto then(Fut f, Work w) -> future<decltype(w(f.get()))> { return async([=]{ w(f.get()); }); } An example of application would be: std::future<int> f = std::async([]{ std::this_thread::sleep_for(std::chrono::microseconds(200)); return 10; }); auto f2 = then(std::move(f), [](int i){ return 2 * i; }); The main thread spawns the tasks but does not wait for any of them to finish. Firstly, future<T> does not have a copy constructor. This means, that the suggested implementation can be only used with shared_future<T> unless we change the call to async() to move the future into the lambda. This SO question suggested a way of doing it but it seems too complicated. I re-implemented the function and I am wondering whether my code is correct or whether I missed something... Secondly, the future that is passed to the then() function might be void so we actually need 2 implementations of then() , right? One for futures returning T and one for futures returning void . Lastly, should the lambda inside the body of then() not have a return statement so that we can actually return the value back? W

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