CW 420

Jon Sneyers, Tom Schrijvers, and Bart Demoen
Guard and continuation optimization for occurrence representations of CHR


Constraint Handling Rules (CHR) is a high-level rule-based language extension, commonly embedded in Prolog. We introduce a new occurrence representation of CHR programs, and a new operational semantics for occurrence representations, equivalent to the widely implemented refined operational semantics. The occurrence representation allows in a natural way to express guard and continuation optimizations, which remove redundant guards and eliminate redundant code for subsumed occurrences. These optimizations allow CHR programmers to write self-documented rules with a clear logical reading. We show correctness of both optimizations, present an implementation in the K.U.Leuven CHR compiler, and discuss speedup measurements.

report.pdf (225K) / mailto: J. Sneyers