// ...

get_map_list(0, 100, [this](std::vector<Map> &map_list) {
    // ...
    for (const auto &map : map_list) {
        Player blah;
        Record rec;

        get_record_by_map(map, [this, blah, rec](Record &record) {
            rec = record;

            get_player(record.player, [this, blah](Player &player) {
                blah = player;
            });
        });
    }
    // ...
});

// ...