HOOPS is an object-oriented Prolog. Procedures that manipulate objects are implemented by object clauses, which have two heads: one to match the pattern of a procedure call, and one to match the pattern of an object. HOOPS has a primitive abstraction facility that allows object definitions to be grouped into classes, but inheritance and other interactions among classes must be explicitly programmed.
This manual describes the syntax of class declarations and other HOOPS language constructs. It includes many example programs, and instructions for loading and executing programs.