Hi all, Sorry for bothering with this. I recently encountered some problems in using boost.lambda with Visual 2010 Express, and need some clues for solving the issue (there are many ways around of course). I simply want to accumulate the values of a std::map, and I thought using lambda to access the second member of the map iterator was appropriate. Here is the piece of code: typedef std::map<T1, unsigned short> m_t; m_t m ; // fill m double acc(0); std::for_each(m.begin(), m.end(), var(acc) += & _1->*& m_t::value_type::second); The last line does not compile on Visual (it does on GCC), I have to add a typedef: typedef typename m_t::value_type aa; std::for_each(m.begin(), m.end(), var(acc) += & _1->*& aa::second); Which one is "more correct" ? To this point, I thought that using accumulate would be cleaner: std::accumulate(m.begin(), m.end(), double(0), & _1->*&aa::second); But I have several compilation errors, and on the top of it: 1>(..)/boost-1_46_1\boost/lambda/detail/member_ptr.hpp(512): error C2296: '->*' : illegal, left operand has type 'const rt0 ' 1> boost/lambda/detail/member_ptr.hpp(622) : see reference to function template instantiation 'RET boost::lambda::detail::member_pointer_action_helper<true,false>::apply<RET,A ,B>(A &,B &)' being compiled 1> with 1> [ 1> RET=unsigned short &, 1> A=rt0, 1> B=rt1 1> ] I do not really understand what rt0/rt1 are. The former should be the iterator::value_type and the latter the pointer to member. Most of all, the call with accumulate looks very similar to the for_each one to me. So, is the problem between the keyboard and the chair ? Best, Raffi