Example: notice the 3rd parameter of sort().

    vector<string> words = {"a", "afd", "fffff", "ew"};
    sort(words.begin(), words.end(),
        [](string a, string b){
            return a.size() < b.size();
        }
    );

Pro: beautiful expression for inline function XD

C++11 Lambda Expression 語法教學與範例