[boost] [lambda] Serialising Lmanda functions

Is there a 'standard' solution to this problem? #include <list> #include <iostream> #include "boost/lambda/lambda.hpp" typedef std::list<unsigned> List; std::ostream & operator<<( std::ostream & s, const List & ); int main( ) { using namespace boost::lambda; List my_list; ( std::cout << _1 << "\n" )( my_list ); } The compiler cannot find a match for operator<<() because the operator and the type are defined in different namespaces, but it's really a nuisance! - Rob.