Analyses, Optimizations and Extensions of Constraint Handling Rules

This is a summary of the Ph.D. thesis of Tom Schrijvers [4]. Constraint Handling Rules (CHR) [3] is a rule-based language commonly embedded in a host language. It combines elements of Constraint Logic Pro-gramming and term rewriting. Several implementations of CHR exist: in Prolog, Haskell, Java and HAL. Typical applications of CHR are in the area of constraint solving, but currently CHR is also used in a wider range of applications, such as type checking, natural language processing and multi-agent systems. In this work we contribute program analyses, program optimizations and extensions of the CHR language. For the optimized compilation of CHR we present several new optimiza-tions: code specialization for ground constraints, anti-monotonic delay avoid-ance, hashtable constraint stores and a new late storage optimization. These and other optimizations have been implemented in a new state-of-the-art CHR system: the K.U.Leuven CHR system [5] which is currently available in SWI