A Polyvariant Binding-Time Analysis for Off-line Partial Deduction

We study the notion of binding-time analysis for logic programs. We formalise the unfolding aspect of an on-line partial deduction system as a Prolog program. Using abstract interpretation, we collect information about the run-time behaviour of the program. We use this information to make the control decisions about the unfolding at analysis time and to turn the on-line system into an off-line system. We report on some initial experiments.Comment: 19 pages (including appendix) Paper (without appendix) appeared in Programming Languages and Systems, Proceedings of the European Symposium on Programming (ESOP'98), Part of ETAPS'98 (Chris Hankin, eds.), LNCS, vol. 1381, 1998, pp. 27-4

Independent AND-parallel implementation of narrowing

We present a parallel graph narrowing machine, which is used to implement a functional logic language on a shared memory multiprocessor. It is an extensión of an abstract machine for a purely functional language. The result is a programmed graph reduction machine which integrates the mechanisms of unification, backtracking, and independent and-parallelism. In the machine, the subexpressions of an expression can run in parallel. In the case of backtracking, the structure of an expression is used to avoid the reevaluation of subexpressions as far as possible. Deterministic computations are detected. Their results are maintained and need not be reevaluated after backtracking

A Web-based Tool Combining Different Type Analyses

Abstract. There are various kinds of type analysis of logic programs. These in-clude for example inference of types that describe an over-approximation of the success set of a program, inference of well-typings, and abstractions based on given types. Analyses can be descriptive or prescriptive or a mixture of both, and they can be goal-dependent or goal-independent. We describe a prototype tool that can be accessed from a web browser, allowing various type analyses to be run. The first goal of the tool is to allow the analysis results to be examined conveniently by clicking on points in the original program clauses, and to highlight ill-typed pro-gram constructs, empty types or other type anomalies. Secondly the tool allows combination of the various styles of analysis. For example, a descriptive regular type can be automatically inferred for a given program, and then that type can be used to generate the minimal “domain model ” of the program with respect to the corresponding pre-interpretation, which can give more precise information than the original descriptive type.