Technical Report: DCC-97-5

An Abstract Machine for an Object Calculus

Luís Lopes, Vasco T. Vasconcelos

Departamento de Ciência de Computadores & LIACC
Faculdade de Ciências, Universidade do Porto
Rua do Campo Alegre, 823 4150 Porto, Portugal

July 1997

Abstract

We present an abstract machine specification for TyCO (Typed Concurrent Objects), a name-passing calculus that aims at capturing fundamental concepts present in Concurrent Object-Oriented Languages. TyCO has built-in labeled messages and ephemeral object s that communicate asynchronously. Persistent objects are supported through instantiation of recursive classes. Concurrency is pervasive and synchronous communication can be implemented by passing continuations in messages. Strong, static typing is provided by a type inference algorithm that supports a form of predicative polymorphism. This paper describes the abstract machine framework in detail, including how it evolves from TyCO and some important properties it can be shown to possess.

Keywords: Object-Oriented, Concurrency, Language, Implementation.