HiLog Programming XSB includes a capapbility to process programs which have complex terms in predicate of functor position. This allows programmers to program in a higher-order syntax, and so this extension of Prolog is called HiLog.
Programmers can think of programming with parameterized predicates or with predicate variables.
HiLog also supports a new way of programming with sets. We will explore these issues in this chapter. HiLog is actually a very simple extension to Prolog. HiLog generalizes this to allow an arbitrary term itself. Computationally these terms are matched just as Prolog terms, so intuitively HiLog programs work very similarly to Prolog programs.