A concurrent constraint handling rules implementation in Haskell with software transactional memory

Constraint Handling Rules (CHR) is a concurrent committedchoice constraint logic programming language to describe transformations (rewritings) among multi-sets of constraints (atomic formulae). CHR is widely used in a range of applications spanning from type system design to artificial intelligence. However, none of the existing CHR implementations we are aware of exploits concurrency or parallelism explicitly. We give a concurrent CHR implementation using GHC (Glasgow Haskell Compiler) with support for Software Transactional Memory. We achieve some significant performance improvements compared to a single-threaded CHR implementation. We obtain a further speed-up, in some cases nearly close to the optimum of 100%, when running programs under under a dual-core processor architecture. Our results show that CHR can be implemented efficiently on a multi-core architecture.

• Type: Conference
• Year: 2007
• Where: POPL
• Authors: Edmund S. L. Lam, Martin Sulzmann
• Keywords: Glasgow Haskell Compiler, Logic Programming Language, POPL 2007, Programming Languages, Software Transactional Memory