LISP as a rapid prototyping environment: The Chinese tutor

Abstract

LISP provides a powerful interactive environment that supports rapid prototyping of complex software. This has always been a main feature of the language, and one that has contributed to its widespread use for experimental applications. Recent years have also seen the development of LISP systems that provide performance comparable with, or better than, that of more traditional programming languages. The next logical step is to show that systems developed in LISP with a rapid-prototyping approach can also provide excellent performance. As an example of the suitability of LISP for rapid prototyping of efficient systems, this article presents a case study where a system was built in a Common Lisp environment out of a series of existing tools. Reliance on existing tools, as well as the interactive features typical of LISP, resulted in extremely rapid prototyping. The system, a computer-based tutor for beginner-level Chinese, was developed in less than three man-weeks. Very rapid development time, however, did not in any way sacrifice performance: the system's performance is quite good and comparable to that of ad hoc systems. This is true of both the interactive component of the program, i.e. the interface to the student, and the database component, which stores the system's knowledge about the Chinese language. The factors that contributed most to the short development time were the extensive reliance on existing tools, the use of an efficient knowledge representation language to implement most of the data structures, and the use of an integrated programming environment. All of these factors were in turn made possible, or at least greatly facilitated, by the choice of LISP as the programming language.