Maintenance aspects of orthogonal extensions to programming languages

A language extension and a system to support evolutionary development of programs are proposed. The proposed framework is a powerful context in which to perform maintenance work. The language extension, called an orthogonal language, addresses both the program structure and its informative context. The language allows interactive and incremental construction of extensions to evolving programs. Such extensions can be debugging fragments, graphic demonstrations and alternative versions. The extensions become part of the structure of the evolving program, but are nevertheless independent of it. Since most nontrivial programs are accompanied by many code fragments that are used to develop and support the programs, a framework that combines the program with its fragments is larger and more informative than the developed program alone. The new program complex offers two advantages: maintenance can use the fragments to support its goals, while the fragments form a better informative context for the maintenance process