User-definable rule priorities for CHR
Proceedings of the 9th ACM SIGPLAN international conference on Principles and practice of declarative programming
Aggregates in constraint handling rules
ICLP'07 Proceedings of the 23rd international conference on Logic programming
Analysing graph transformation systems through constraint handling rules
Theory and Practice of Logic Programming
Hi-index | 0.01 |
We propose an extension of Constraint Handling Rules (CHR) with aggregates such as sum, count, findall, and min. This new feature significantly improves the conciseness and expressiveness of the language. In this paper, we describe an implementation based on source-to-source transformations to CHR (extended with some low-level compiler directives). We allow user-defined aggregates and nested aggregate expressions over arbitrary guarded conjunctions of constraints. Both an on-demand and an incremental aggregate computation strategy are supported.