struct Pos { int x, int y; };

class Snake {
    list<Pos> body;
    Direction dir;
    void move();

public:
    void mainLoop();
};

void Snake::mainLoop(){
    while (true){
        sleep(10);
        move();
    }
}

void Snake::move(){
    if (dir == stop){ return; }

    body.pop_back();

    Pos oldHead = *(body.begin()); // get the first element of the list
    Pos newHead = oldHead;

    switch (dir){
        case left: newHead.x--; break;
        case right: newHead.x++; break;
        case up: newHead.y--; break;
        case down: newHead.y++; break;
    };

    body.push_front(newHead});
}