Transforming Coroutining Logic Programs into Equivalent CHR Programs

TL;DR

This paper presents a method to transform coroutining logic programs into equivalent CHR programs that maintain the same behavior under standard execution, improving readability and static analysis capabilities.

Contribution

It introduces a synthesis technique that converts coroutining logic programs into CHR programs with only simplification rules, enhancing portability and analysis.

Findings

Transformed CHR programs are more concise and readable.

The synthesis preserves the original program's computational behavior.

The approach facilitates static analysis of logic programs.

Abstract

We extend a technique called Compiling Control. The technique transforms coroutining logic programs into logic programs that, when executed under the standard left-to-right selection rule (and not using any delay features) have the same computational behavior as the coroutining program. In recent work, we revised Compiling Control and reformulated it as an instance of Abstract Conjunctive Partial Deduction. This work was mostly focused on the program analysis performed in Compiling Control. In the current paper, we focus on the synthesis of the transformed program. Instead of synthesizing a new logic program, we synthesize a CHR(Prolog) program which mimics the coroutining program. The synthesis to CHR yields programs containing only simplification rules, which are particularly amenable to certain static analysis techniques. The programs are also more concise and readable and can be ported to CHR implementations embedded in other languages than Prolog.