how c++ std::function bind to a template function?

is there any mechanism that can be used to implement code as follows:

// T can be any type
std::function<T(int,int)> tf;

tf = [](int x, int y) -> int{
    return x + y;
};

cout << tf(4, 5) << endl;

tf = [](int x, int y) -> string{
    return "hello world";
}
cout << tf(4,5) << endl;