Recursive Lambda in C ++

The C ++ Standards Committee is really too rigid. Since Lambda is added to C ++, the standard definition of Lambda is applied step by step without adding a self-Reference Mechanism of Lambda. After searching for half a day, except for the fix point + Y Combinator, which could make 99% of students dizzy, one of the most practical solutions is to import Lambda bind to STD :: function <...>.

My code that requires recursive lambda:

  void print_output() const { // use recursive lambda        std::string str;        std::function<void(state_id_t,state_id_t,char_t)> lambda =        [&](state_id_t source,state_id_t target,char_t c) {            str.push_back(c);            if (is_term(target))                cout <<str << '\n';            for_each_move(target, lambda);            str.resize(str.size()-1); // pop_back        };        for_each_move(initial_state, lambda);    }

The tree shape automata code is printed in DFS order. for various reasons (memory, speed, and conciseness), a general for_each_move is designed to traverse each direct target of the specified state.

If there is recursive lambda, this code should be more concise and efficient (assuming [[] is the symbol that references Lambda itself ):

    void print_output() const { // use recursive lambda        std::string str;        for_each_move(initial_state, [&](state_id_t, state_id_t target, char_t c) {            str.push_back(c);            if (is_term(target))                cout <<str << '\n';            for_each_move(target, [[]]);            str.resize(str.size()-1); // pop_back        });    }

This is the intention of C ++ committee! It is to make everyone uncomfortable, to show their pure academic, their pure mathematic!
It is easy to add a self-referenced symbol!