Just as a side note: if you're looking to write a convenience wrapper like the author's transformVec, do not have it take the function as `const function<T(T)>&

Just as a side note: if you're looking to write a convenience wrapper like the author's transformVec, do not have it take the function as `const function<T(T)>&`. Instead, do something like: template <typename T, typename F> vector<T> transformVec(const vector<T>& v, F op) Using std::function in a case where you just want something callable just makes the optimizer's job a lot harder. Using std::function is a good idea if you actually need type erasure (for example if you want to pass something callable to a function that is not a template).