#include <boost/variant.hpp>

#include <iostream>
#include <limits>
#include <map>

typedef boost::make_recursive_variant<
    int,
    std::map<float, boost::recursive_variant_>
>::type element;

// Use this typedef as a stand-in for the second type in your variant
typedef std::map<float, element> map_t;

struct printer : public boost::static_visitor<> {
    template<typename T>
    void operator () (const T& t) const {
        m_os << t;
    }

    void operator () (const map_t& m) const {
        m_os << '{';
        typedef map_t::const_iterator iterator;
        for (iterator i = m.begin (), e = m.end (); i != e; ++i) {
            if (i != m.begin())
                m_os << ", ";
            m_os << '(' << i->first << ", ";
            boost::apply_visitor (*this, i->second);
            m_os << ')';
        }
        m_os << '}';
    }

    printer (std::ostream& os) : m_os (os) {}

    ~printer () { m_os << std::endl; }

private:
    mutable std::ostream& m_os;
};

int main ()
{
    element i = 42;

    map_t the_map;

    the_map.insert (std::make_pair (1.23f, i));
    the_map.insert (std::make_pair (3.14159f, std::numeric_limits<int>::max()));
    the_map.insert (std::make_pair (2.46f, the_map));

    printer (std::cout).operator() (the_map);

    return 0;
}