Herbrand constraints in HAL

Bart Demoen, Maria Jose Garcia De La Banda, Warwick Harvey, Kim George Marriott, David Matthew Overton, Peter J Stuckey

    Research output: Chapter in Book/Report/Conference proceedingChapter (Book)Researchpeer-review


    Mercury is a logic programming language that is considerably faster than traditional Prolog implementations, but lacks support for full unification. HAL is a new constraint logic programming language specifically designed to support the construction of and experimentation with constraint solvers, and which compiles to Mercury. In this paper we describe the HAL Herbrand constraint solver and show how by using PARMA bindings, rather than the standard WAM representation, we can implement a solver that is compatible with Mercury’s term representation. This allows HAL to make use of Mercury’s more efficient procedures for handling ground terms, and thus achieve Mercury-like efficiency while supporting full unification. An important feature of HAL is its support for user-extensible dynamic scheduling since this facilitates the creation of propagation-based constraint solvers. We have therefore designed the HAL Herbrand constraint solver to support dynamic scheduling. We provide experiments to illustrate the efficiency of the resulting system, and systematically compare the effect of different declarations such as type, mode and determinism on the resulting code.
    Original languageEnglish
    Title of host publicationProgram Development in Computational Logic
    Subtitle of host publicationA Decade of Research Advances in Logic-Based Program Development
    EditorsMaurice Bruynooghe, Kung-Kiu Lau
    Place of PublicationBerlin Germany
    Number of pages40
    ISBN (Print)3540221522
    Publication statusPublished - 2004

    Publication series

    NameLecture Notes in Computer Science
    ISSN (Print)0302-9743

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