Class partition

example/tutorial/appendix_mpl.cpp:333–342

template <typename Sequence, typename Pred>
struct partition {
    using hana_pair = decltype(hana::partition(
        hana::to_tuple(Sequence{}),
        detail::mpl_predicate<Pred>
    ));
    using type = pair<
        decltype(hana::first(hana_pair{})),
        decltype(hana::second(hana_pair{}))
    >;
};

template <typename Sequence, typename Pred = mpl::quote2<less>>
struct sort {