#include <iostream>
#include <boost/fusion/include/mpl.hpp>
#include <boost/fusion/include/container.hpp>
#include <boost/fusion/include/sequence.hpp>
#include <boost/fusion/include/functional.hpp>
#include <boost/mpl/placeholders.hpp>
#include <boost/mpl/transform.hpp>

namespace fusion=boost::fusion;
namespace mpl=boost::mpl;

struct Arg1;
struct Arg2;

template<typename Seq>
double
hf(Seq const& s)
{
  std::cout << fusion::at_key<Arg1>(s) << std::endl;
  std::cout << fusion::at_key<Arg2>(s) << std::endl;
  return fusion::at_key<Arg1>(s)+fusion::at_key<Arg2>(s);
}

template<typename>
struct ditch_references;
template<typename P>
struct ditch_references<P&>
{
  typedef fusion::pair<typename P::first_type, typename P::second_type> type;
};

struct foo
{
  typedef double result_type;
  template<typename Seq>

  double
  operator()(Seq const& seq)const
  {
    //the elements of Seq are reference-qualified!
    return hf(
      fusion::result_of::as_map<
        mpl::transform<Seq const, ditch_references<mpl::_1> >::type
      >::type(seq));
  }
};
fusion::unfused<foo> h;

typedef fusion::pair<Arg1, int> Arg1_t;
typedef fusion::pair<Arg2, double> Arg2_t;

int main()
{
  std::cout << h(Arg1_t(123), Arg2_t(321.123)) << std::endl;
  std::cout << h(Arg2_t(321.123), Arg1_t(123)) << std::endl;
}