Specification in Fresco

Fresco [Wills 1991] is a programming environment which provides for the rigorous development of object-oriented software from specifications. Specifications are in¬corporated into the software in the form of abstract classes; and the specification elements of the language can also be used in concrete classes to document the im¬plementations and their development in a style similar to that of [Morgan 1990]. It is interesting to contrast Fresco with object-oriented styles of specification: firstly because it is based on VDM [Jones 1986], rather than Z; and secondly because of its emphasis on specifying program modules, rather than modularizing specifications.