Canonical Abstract Syntax Trees

This paper presents Gom, a language for describing abstract syntax trees and generating a Java implementation for those trees. Gom includes features allowing the user to specify and modify the interface of the data structure. These features provide in particular the capability to maintain the internal representation of data in canonical form with respect to a rewrite system. This explicitly guarantees that the client program only manipulates normal forms for this rewrite system, a feature which is only implicitly used in many implementations

Term collection in lambda/rho-calculi

International audienceThe ρ-calculus generalises term rewriting and the λ-calculus by defining abstractions on arbitrary patterns and by using a pattern-matching algorithm which is a parameter of the calculus. In particular, equational theories that do not have unique principal solutions may be used. In the latter case, all the principal solutions of a matching problem are stored in a “structure” that can also be seen as a collection of terms. Motivated by the fact that there are various approaches to the definition of structures in the ρ-calculus, we study in this paper a version of the λ-calculus with term collections. The contributions of this work include a new syntax and operational semantics for a λ-calculus with term collections, which is related to the λ-calculi with strict parallel functions studied by Boudol and Dezani et al. and a proof of the confluence of the β-reduction relation defined for the calculus (which is a suitable extension of the standard rule of β-reduction in the λ-calculus)

Rules and Strategies in Java

International audienceIn this paper we present the essential feature we have considered when designing a new language based on rules and strategies. Relying on the implementation of Tom, we explain how these ingredients can be implemented and integrated in a Java environment

Rewriting Strategies in Java

International audienceIn any language designed to express transformations, the notion of rewrite rule is a key feature. Its conciseness as well as its strong theoretical foundations are essential. The notion of strategy is complementary: this describes how rules are applied. In this paper, we show how a high-level strategy language can be implemented in a Java setting. We present the integration of the visitor combinator design pattern into Tom. This corresponds to an interpreter for strategy expressions. To be more efficient, we present a compilation method based on bytecode specialization. This low-level transformation is expressed in Tom itself, using rules and strategies

Confluence de calcul à motifs

Dans ce rapport, nous proposons une preuve de confluence générique qui poura être instanciée pour les différents calculs. Pour cela, nous nous intéresserons au lambda-calcul dynamique qui axiomatise la manière dont l'abstraction est réduite. Nous utilisons cette preuve pour l'étendre au cas où le filtrage est fait modulo une théorie, ici la commutativité. Intuitivement il faut que le filtrage soit stable par substitution, par réduction et par équivalence. Nous caractérisons aussi une classe d'algorithmes de filtrage qui conduisent à des calculs non confluents

Effective Strategic Programming for Java Developers

International audienceIn object programming languages, the Visitor design pattern allows separation of algorithms and data-structures. When applying this pattern to tree-like structures, programmers are always confronted with the difficulty of making their code evolve. One reason is that the code implementing the algorithm is interwound with the code implementing the traversal inside the Visitor. When implementing algorithms such as data analyses or transformations, encoding the traversal directly into the algorithm turns out to be cumbersome as this type of algorithm only focuses on a small part of the data-structure model (e.g., program optimization). Unfortunately, typed programming languages like Java do not offer simple solutions for expressing generic traversals. Rewrite-based languages like ELAN or Stratego have introduced the notion of strategies to express both generic traversal and rule application control in a declarative way. Starting from this approach, our goal was to make the notion of strategic programming available in a widely used language such as Java and thus to offer generic traversals in typed Java structures. In this paper, we present the strategy language SL that provides programming support for strategies in Java