myasync work in progress v3

#include <future>
#include <thread>
#include <iostream>
#include <string>
#include <vector>

std::string thFun() {
    throw std::exception("bang!");
    return "val";
}


std::future<std::string> myasync()
{
    auto prms = std::make_shared<std::promise<std::string>> ();

    std::future<std::string> fut = prms->get_future();
    std::thread th([=](){

        try {
            std::string val = thFun();

            prms->set_value(val);

        } catch(...) {
            prms->set_exception(std::current_exception());
        }

     });

    th.detach();
    return fut;
}

 int main() {

    auto fut = myasync();

    try {
        auto res = fut.get();
        std::cout << "Result: " << res << std::endl;

    } catch(const std::exception& exc) {
        std::cout << "Exception: " << exc.what() << std::endl; //"Exception: future already retrieved"
    }

 }