Hello, I encountered a problem using a sequence obtained by mpl::joint_view with make_variant_over. While I can make a variant over a sequence of types, I can't make the variant over two typesequences joined together with joint_view. I am really new with mpl, so I might just have done something really wrong. The program is below, the line commented out produces lots of errors when uncommented. Is this a problem in either the variant or the mpl library, or did I just do something wrong? thanks, Richard Peters #include <boost/mpl/vector.hpp> #include <boost/mpl/joint_view.hpp> #include <boost/variant.hpp> namespace mpl { using namespace boost::mpl; } struct a {}; struct b {}; int main() { typedef mpl::vector<a> list1; typedef mpl::vector<b> list2; typedef mpl::joint_view<list1, list2>::type joint_list; typedef boost::make_variant_over<list1>::type variant_type1; typedef boost::make_variant_over<joint_list>::type variant_type2; a x; variant_type1 y(x); //variant_type2 z(x); // doesn't compile }