Integrating Java and Prolog through Generic Methods and Type Inference

P@J is a framework, based on the tuProlog open-source engine, allowing Prolog code to be used as possible implementation of a Java method: Java annotations are used for specifying all the necessary information to fill the Java-Prolog gap. This framework is useful to inject a declarative, logic-based paradigm into mainstream ob ject-oriented programming, so as to easily code functionalities related to automatic reasoning, adaptivity, and conciseness in expressing algorithms.

In this paper, an extension of P@J is presented which improves the invocation technique for such Prolog-implemented methods. Java type inference of generic method calls is intensively used to automatically infer all the necessary paradigm mismatch information: this results in an elegant and concise invocation style, which further reduces the gap between Prolog goal satisfaction and Java method invocation. This new approach inspires some interesting applications: we show examples related to the implementation of abstract data types and parsers for context-free grammars.