Appeared in Volume 9/4, November 1996
RELFUN is a LP language with call-by-value (eager) expressions of non-deterministic, non-ground functions. Clauses are 'hornish', succeeding with true, or 'footed', returning values. They define operations (relations and functions) permitting apply-reducible higher-order syntax with arbitrary terms as operators.
Finite domains and exclusions, as well as sorts, are first-class citizens build into unification.
Extensions include single-cut clauses and relational-functional primitives such as a value-returning tupof.
Versions of RELFUN are used in the hybrid COLAB shell and in VEGA's Declarative Representation Language.
For more details, contact:
Harald Boley and Michael Sintek