Hello, I am having problems getting fusion sequences to work with MPL. The docs indicate this should be possible , e.g. the "Adapted" page states, "Fusion sequences may also be adapted as fully conforming MPL sequences (see Intrinsics)." I couldn't find more information on the Intrinsics page regarding the use of fusion sequences with MPL, but I tried: #include <boost/mpl/is_sequence.hpp> #include <boost/fusion/container/vector.hpp> #include <boost/fusion/sequence/intrinsic.hpp> int main() { BOOST_MPL_ASSERT(( boost::mpl::is_sequence<fusion::vector<int> > )); } And got a mess of errors from mpl::is_sequence<fusion::vector<int> >: (gcc 4.0.1/darwin) /Development/boost/boost/mpl/begin_end.hpp: In instantiation of 'boost::mpl::begin<boost::fusion::vector<int, boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, boost::fusion::void_> >': [snip errors] /Development/boost/boost/mpl/begin_end.hpp:35: error: invalid use of undefined type 'struct boost::mpl::begin_impl<boost::fusion::fusion_sequence_tag>' [...more errors] I tried things other than is_sequence (like mpl::at), but got similar errors. What am I missing? Thanks for any suggestions! Stjepan