I have class that is parameterized by several type (Boost::Unit units type). template<class U1, class U2, ... > class A{ A(quantity<U1> q1, quantity<U2> q2, ... ){} }; since the number of arguments is arbitrary I though it would be a good idea to use either MPL sequence and Tuples. Or better yet a fusion::vector. so the class will be parametrized by a fusion::vector or unit types. template<class FusionOfUnits> //or class MPLofUnits class A{ A(FusionOfQuantities fq){} //or TupleOfUnits }; The questions is: ¿what is the best way to transform a fusion::vector<unit1, unit2, unit3, ..., unitN > into a fusion::vector<quantity<unit1>, quantity<unit2>, quantity<unit3>, ..., quantity<unitN> > whete the N is (compile-time) arbitrary, i.e. the lenght of the fist fusion::vector is arbitrary (If you are not familiar with Boost.Units, unitN is just a type and quantity is a template type.) Thank you, Alfredo