Languages that support abstraction and modular structure, such as Standard ML, Modula, Ada, and (more or less) C++, may have deeply nested dependency hierarchies among source files. In ML the problem is particularly severe because ML's powerful parameterized module (functor) facility entails dependencies among implementation modules, not just among interfaces.

ion and Representation Independence: Through abstraction, the details of an application 's components can be hidden, providing a broad perspective on the design. This in turn allows changes to be made to the internal structure and function of each component, achieving representation independence since the external view of an module/ADT is not impacted. ffl Incrementality/Anticipation of Change: The design process at all times is iterative or incremental. This is true whether a given set of modules/ADTs represents an initial or final design for an application. There is an expectation that components will be changed, added, refined, etc., as needed to support evolving requirements. ffl Cohesion/Coupling: An application is cohesive if each component does a single, well-defined task. Cohesion has a long history in computing. In the `early days', the rule of thumb was that each procedure or function should be limited to one output page (approximately 60 lines). If so, then the resulting s...

Software design is not an isolated activity, and in the opinion of some, is one of the most \Lambda Copyright cfl1996 by S. A. Demurjian, Storrs, CT.