Prolog at IBM: An advanced and evolving application development technology

Prolog is a powerful programming language, based on logic, that originated and matured in Europe. This paper aims to show that Prolog is becoming one of the key tools for the entire application development community. First explained is how the unique properties of Prolog give it many advantages over classical languages. Then we show that the language is sufficiently mature technically so that numerous industrial Prolog products are now available. In particular, IBM offers the Systems Application Architecture® (SAA™) AD/Cycle™ Prolog product family, which provides a combination of logic programming and object programming facilities. Many industrial applications are written in Prolog. Examples of 15 outstanding operational applications, developed by IBM or major IBM customers, are presented. There is a potential for future growth in the types of applications enabled by improving the language. The simplicity and elegance of the theoretical basis of Prolog allow a number of extensions to be defined. Here, three European projects are briefly presented. In conclusion it is shown that Prolog, possibly extended in many directions, is one of the tools that could help solve the long-standing quality and cost problems in application development.