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Thanks, iterator_range works fine. What's not very nice to me is the T typename is lost for empty sequence and after using a metafunction, so vector_c is not really usable for metaprograming, its just a macro to easier define a vector.

Well... Type never gets lost in C++ ;) What about: typedef mpl::vector_c my_vector; BOOST_MPL_ASSERT(( is_same< mpl::front::type::value_type, float > )); vector_c initializes a vector with integral_c derived type (like mpl::int_ or mpl::bool_) and value specified, so in this example we have most probably an mpl::vector of integral_c,..., integral_c. Anyway applying a front metafunction to any element of vector will return some integral_c specification. Since you are interested in type contained in integral_c you can access it via integral_c::value_type. Therefore: mpl::front::type::value_type ^^^^ ^^^^^ + => integral_c::value_type + => integral_c result in correct type resolution stored in mpl::vector. Hope that helps. With Kind Regards, Ovanes Markarian