Towards a Generic Trace for Rule Based Constraint Reasoning

TL;DR

This paper introduces a comprehensive, generic tracing framework for Constraint Handling Rules (CHR) that enhances debugging and analysis across various implementations by extending the formal semantics.

Contribution

It proposes a new, formalized generic trace for CHR that captures detailed execution information, improving debugging and analysis capabilities.

Findings

The proposed trace can analyze any aspect of CHR execution.

It is compatible with multiple CHR implementations.

The trace is derived from the formal $ ext{omega}_r^ ext{lor}$ semantics.

Abstract

CHR is a very versatile programming language that allows programmers to declaratively specify constraint solvers. An important part of the development of such solvers is in their testing and debugging phases. Current CHR implementations support those phases by offering tracing facilities with limited information. In this report, we propose a new trace for CHR which contains enough information to analyze any aspects of \CHRv\ execution at some useful abstract level, common to several implementations. %a large family of rule based solvers. This approach is based on the idea of generic trace. Such a trace is formally defined as an extension of the $\omega_r^\lor$ semantics of CHR. We show that it can be derived form the SWI Prolog CHR trace.