A new notion of encapsulation
David Gries, Jan F. Prins · 1985
Generally speaking, a “module” is used as an “encapsulation mechanism” to tie together a set of declarations of variables and operations upon them. Although there is no standard way to instantiate or use a module, the general idea is that a module describes the implementation of all the values of a given type. We believe that this is too inflexible to provide enough control: