boost::hana::drop_front doesn't respect refness

[KierenP]

#include <boost/hana/ext/std/tuple.hpp>
#include <boost/hana/fold_left.hpp>
#include <boost/hana/find_if.hpp>
#include <boost/hana/for_each.hpp>
#include <boost/hana/transform.hpp>
#include <boost/hana/tuple.hpp>
#include <boost/hana/type.hpp>

#include <iostream>
#include <tuple>
#include <vector>

namespace hana = boost::hana;

int main()
{
    int x = 1;
    int y = 2;
    int z = 3;

    std::tuple<int&, int&, int&> refs {x, y, z};
    auto ref_drop = boost::hana::drop_front(refs);

    x = 10;
    y = 20;
    z = 30;

    std::cout << x << " " << y << " " << z << std::endl;
    std::cout << std::get<0>(refs) << " " << std::get<1>(refs) << " " << std::get<2>(refs) << std::endl;
    std::cout << std::get<0>(ref_drop) << " " << std::get<1>(ref_drop) << std::endl;
}

The output of the above code is:

10 20 30
10 20 30
2 3

Expected output is:

10 20 30
10 20 30
20 30

I would expect if I pass boost::hana::drop_front a std::tuple<T&, U&, V&> to get back a std::tuple<U&, V&> but instead I get a std::tuple<U, V>. This is unexpected. Is this intended behavior?

[KierenP]

As an aside, what is the best way to iterate over tuple elements until a condition is true? For example if I have a std::tuple (std::tuple<X, Y, Z>) and I want to call .fn(...) on each element I can do it like this:

    boost::hana::for_each(my_tuple, [](auto&& x) 
    { 
        x.fn();
    });

But if I want to iterate only until a precondition is hit, I can't figure out how to do this

    auto first_ok_result = boost::hana::for_each(my_tuple, [](auto&& x) 
    { 
        auto result = x.fn();
        if (result.status == status::ok)
            return result.value; // I want to stop the for_each and return this value
    });