Function main

example/struct/foldable.cpp:20–31

};

int main() {
    constexpr Kitten kitten{5, 10, 0};

    BOOST_HANA_CONSTEXPR_CHECK(
        hana::fold_left(kitten, 0, [](auto total, auto member) {
            // first(member) is the name of the member, here
            // "extremely_cute", or "cute" or "not_so_cute",
            // and second(member) is its value.
            return hana::second(member) + total;
        }) == (5 + 10 + 0)
    );
}