entity user {
    key name;
    mutable points: integer = 0;
}

entity item {
    name;
    key id: integer;
    owner: user;
}

operation create_user(name) {
    create user(name);
}

operation add_item(user_name: text, item_name: text, item_id: integer) {
    val u = user @ { .name == user_name };
    create item(item_name, item_id, u);
    u.points += 10;
}

query get_user_items(user_name: text) {
    return item @* { .owner.name == user_name } ( $.name, $.id );
}

query get_top_users(limit: integer) {
    return user @* {} ( @sort_desc .points, .name ) limit limit;
}