[Boost-users] [fusion] transform a heterogeneous vector

In the example from the documentation : struct triple { typedef int result_type; int operator()(int t) const { return t * 3; }; }; ... assert(transform(make_vector(1,2,3), triple()) == make_vector(3,6,9)); ...all the elements have the same type. How can it work with heterogeneous vectors ? What would be typedef'ed to result_type ? Jean-Louis