Dr. Dobb's Journal June 1997

CLIPS: C Language Integrated Production System

CLIPS is a nonprocedural language that supports system development across three distinct programming paradigms -- rule-based, object-oriented, and procedural:

• Rule-based programming allows knowledge to be represented as heuristics, or "rules of thumb," which specify a set of actions to be performed for a given situation.
• Object-oriented programming (OOP) allows complex systems to be modeled as modular components (which can be easily reused to model other systems or to create new components).
• Procedural programming capabilities provided by CLIPS are similar to capabilities found in languages such as C, Pascal, Ada, and LISP.

CLIPS is written in ANSI C for portability and speed and has been installed on many different computers without code changes. I compiled CLIPS to run on my Amiga computer. CLIPS can be embedded within procedural code, as a subroutine, and integrated with languages such as C, FORTRAN, and Ada. CLIPS can be extended by a user through the use of several well-defined protocols.

CLIPS was developed by the NASA Software Technology Branch (STB -- formerly the Artificial Intelligence Section) in Clear Lake, Texas. STB intended CLIPS to overcome three problems with LISP-based expert system tools within NASA: the low availability of LISP on a wide variety of conventional computers, the high cost of state-of-the-art LISP tools and hardware, and the poor integration of LISP with other languages (making embedded applications difficult.)

CLIPS is a mature language. The first release of CLIPS to groups outside of NASA, Version 3.0, occurred in the summer of 1986. Its development has coincided with that of Smalltalk and C++. A contractor maintains it, making minor releases when necessary to fix bugs or provide minor new capabilities. The most recent version of CLIPS is 6.04. Version 6.05 will be released in the near future.

The standard version of CLIPS provides an interactive, text-oriented development environment, including debugging aids, on-line help, and an integrated editor. CLIPS documentation consists of a reference manual, users' guide, and architecture manual.

The CLIPS home page is at http://www.jsc.nasa.gov/~clips/CLIPS.html. CLIPS 6.04 executables for Windows (16- and 32-bit) are available at http://www.ghgcorp.com/clips/download/executables/pc/, CLIPS FAQs are available at http://www.ghgcorp.com/clips/CLIPS-FAQ, and the CLIPS list-server is at [email protected].

-- J.S.