JFun: Functional Programming in Java

A function is a good way of specifying a computation since in each computation the result depends in a certain way on the parameters, and using functions makes a program modular and well-structured. In order to reduce the development effort and future programming costs caused by bugs and maintenance problems, writing well-structured and modular programs has become crucial as software becomes more and more complex. Since modularity is the key to successful programming, functional languages are vitally important to the real world. In this paper we try to show that writing programs in an object-oriented language by using functional programming concepts is possible. As examples, list and tree manipulation functions, numerical integration and differentiation, and alpha-beta heuristic which is an algorithm from Artificial Intelligence used in game-playing programs are implemented in Java programming language using functional programming concepts.