This example, from the docs, won't compile with linux g++3.4.3 typedef map< pair<int, char> , pair<double, std::string> > map_type; map_type m( make_pair<int>('X') , make_pair<double>("Men")); int main() { std::cout << at<int>(m) << std::endl; std::cout << at<double>(m) << std::endl; }