Objects as Modules in Newspeak

We describe support for modularity in Newspeak, a new pro- gramming language descended from Smalltalk (34) and Self (70). Like Self, all computation — even an object's own ac- cess to its internal structure — is performed by invoking methods on objects. However, like Smalltalk, Newspeak is class-based. Classes can be nested arbitrarily, as in Beta (47). Since all names denote method invocations, all classes are virtual; in particular, superclasses are virtual, so all classes act as mixins. Unlike its predecessors, there is no static state in Newspeak, nor is there a global namespace. Top level classes act as module definitions, which are independent, immutable, self-contained parametric namespaces. They can be instantiated into modules which may be stateful and mu- tually recursive. Naturally, like its predecessors, Newspeak is reflective: a mirror library allows structured access to the program meta-level