Aleksey, With gcc (GCC) 3.3.3 (cygwin special) there is a include order dependency. Including boost/bind.hpp before boost/mpl/transform.hpp causes a compile error type named `type' in `struct boost::mpl::apply_wrap2<boost::mpl::push_front<mpl_::na, mpl_::na>, mpl_::arg<1>, wrapper<mpl_::arg<2> > >' I have not been able to test with other gcc versions. Regards, Hugo #include "boost/bind.hpp" #include "boost/mpl/transform.hpp" #include <boost/mpl/apply.hpp> #include <boost/mpl/list.hpp> #include <boost/mpl/equal.hpp> #include <boost/mpl/assert.hpp> // computed type template <typename T> struct wrapper{}; // metafunction class to compute type struct wrapped_type { template <typename T> struct apply { typedef wrapper<T> type; }; }; void test_transform() { typedef boost::mpl::list<int, char> typelist; typedef boost::mpl::list< wrapper<int>, wrapper<char> > wrapped_typelist; typedef boost::mpl::transform< typelist, wrapped_type >::type result; BOOST_MPL_ASSERT(( boost::mpl::equal<wrapped_typelist, result> )); }