An interface between Java and APL

Abstract

This paper discusses an interface between the Java and APL languages. It is in the form of a report on some technology that has been developed for SHARP APL, though there are no aspects of the technology that are particularly special to that dialect of APL.The interface (called, for the purposes of this paper, the "APL-Java Interface") is a general facility for allowing APL programs and Java programs to work together. The project was started because it occurred to us that there is now a substantial body of Java-based technology that solves many of the problems that we needed to address for APL, particularly in the area of program interoperability; and, since this Java-based technology is both widely (and, in many cases, freely) available, and portable across the platforms that are of most concern to us, it would make a lot of sense to try to develop a general way to access this technology from APL. If that could be done, we could largely avoid re-inventing the wheel in a whole set of instances, by capitalizing on existing Java-based solutions. As a simple example, rather than implementing the standard XML parser in APL (which is certainly possible), we could simply use one of the several existing Java implementations.There are four parts to this paper:• A very brief discussion of Java is given.• An overview of the APL-Java Interface is presented, with some examples.• Some practical uses for the interface are presented.Some aspects of the interface that are of some technical interest are discussed.• The dialect of APL used in code examples in this paper is SHARP APL.A knowledge of Java will certainly help with this paper, but the dependency on such knowledge is not all that heavy, so it is quite likely that most of the paper's points can be grasped given just the few simple Java notions listed below.