Compilation of Nonprocedural Specifications into Computer Programs

摘要

The article describes the compilation of a program specification written in the Very high Level nonprocedural MODEL language into an object (PL/I or Cobol) procedural language program. Nonprocedural programming languages are descriptive and devoid of procedural controls. They are therefore easier to use and require less programming skills than procedural languages. First, the MODEL language is briefly presented and illustrated. An important phase in the compilation process is the representation of the specification by a dependency graph denoted as array graph which expresses the interdependency between statements. Two classes of algorithms which utilize this graph representation continue the compilation process. The first class checks various completeness, non-ambiguity and consistency aspects of the specification. Upon detesting any faults the system attempts some automatic correcting measures which are reported to the user. Alternately when no feasible corrections are possible it reports an error and solicits a user modification.