oostpro.com/mplbook" target="_top">MPL book</a> with actions
                    defined as pointers to state or state machine methods. The second one is based
                    on functors. The third, eUML (embedded UML) is an experimental language based on
                    Boost.Proto and Boost.Typeof and hiding most of the metaprogramming to increase
                    readability. Both eUML and the functor front-end also offer a functional library
                    (a bit like Boost.Phoenix) for