It provides a means for the derivation of executable expressions from initial specifications. A specification language of expressions is described, which includes construct for reasoning about undefined terms and non-deterministic expressions, as well as improper expressions. Examples are used to illustrate how and why each type of expression might arise. An outline is given of how refinement of specifications might proceed, and a refinement relation is defined using six actions. Despite the existence of aids for programming, errors in programming development remain, and often prove very costly.
Much more work is required in error management.
This paper shows how error classifications can provide useful error management information. A number of error classifications already exist. Along with looking at some of these existing classifications, two classifications of looping errors are presented in this paper. The motivation behind the developed classifications is to relate a task under development to an existing repository of programming information which is stored according to the developed classifications. The relation of such information may assist one or more users working on the same or similar programming tasks.