Dynamic Type Information in Process Types

                          Franz Puntigam
    Institut für Computersprachen, Technische Universität Wien
           Argentinierstraße 8, A-1040 Vienna, Austria
             E-mail: franz@complang.tuwien.ac.at

Static checking of process types ensures that each object accepts all
messages received from concurrent clients, although the set of acceptable
messages can depend on the object's state. However, conventional approaches
of using dynamic type information (e.g., checked type casts) are not
applicable in the current process type model, and the typing of self-
references is too restrictive. In this paper a refinement of the model is
proposed. It solves these problems so that it is easy to handle, for example,
heterogeneous collections.