A CPS-semantics for a typed lambda-calculus of exception handling with fixed-point

Colloque avec actes et comité de lecture.We propose to add a fixed-point combinator to a lambda- calculus of exception handling whose type system corresponds to classical logic through the Curry-Howard isomorphism. To this end, we here give a CPS-semantics to the calculus and show that for non-exceptional terms, this semantics possesses the property of computational adequacy

A confluence Result for a Typed lambda-Calculus of Exception Handling with Fixed-point

Colloque avec actes et comité de lecture.We prove the confluence of a lambda-calculus of exception handling whose typing system and evaluation rules are initially based on classical logic through the Curry-Howard isomorphism and to which we have added a general fixed-point operator

Une approche contrôlée du traitement d'exceptions en programmation fonctionnelle

Texte intégral accessible uniquement aux membres de l'Université de LorraineBy analysing the way ML exceptions can escape their scope of declaration, Philippe de Groote proposed in TLCA'95 a simply typed lambda-calculus of "static" exception handling ensuring that a well typed term cannot lead to a uncaught exception. The underlying idea was to keep the handlers active during the entire execution of the program. We propose a study of this concept in a realistic programming context authorizing general recursion by means of a fixed-point operator. The resulting calculus is described using three semantical forms: reduction rules, operational semantics and CPS semantics. We establish that these three interpretations are equivalent for a particular class of terms (the programs), thus showing that static exception handling can sometimes be considered as an acceptable alternative to classical, "dynamic" exception handling.A partir de l'analyse du processus par lequel des exceptions en ML peuvent échapper à leur champ de déclaration, Philippe de Groote a proposé lors de TLCA'95 un lambda-calcul simplement typé de traitement d'exceptions statique assurant qu'un terme correctement typé ne pouvait donner lieu à une exception non capturée. Le principe permettant d'aboutir à un tel résultat consiste à garantir que chaque gestionnaire d'exception reste accessible pendant toute la durée d'exécution du programme. Nous nous proposons d'étudier ce concept dans un cadre de programmation réaliste autorisant la récursion générale par l'ajout au calcul d'un opérateur de point fixe.Le calcul ainsi obtenu est présenté sous trois formes sémantiques:respectivement un système de règles de réduction, une sémantique opérationnelle et un modèle dénotationnel basé sur la notion de transformation par continuations. En établissant que ces trois interprétations sont équivalentes sur une classe particulière de termes (les programmes), nous montrons en quoi l'approche statique du traitement d'exceptions peut être considérée dans certains cas comme une alternative raisonnable au traitement classique

Du Mu : comment rendre justice à l'homme et à l'œuvre ?

Verniau Pilière Marie-Christine. Du Mu : comment rendre justice à l'homme et à l'œuvre ?. In: Études chinoises, vol. 6, n°2, Automne 1987. pp. 47-71

On the semantics of static exception handling

Rapport interne.We study an idealized programming language (lambda-exn) that features a static variant of ML-like exception handling. We present three different kinds of semantics: an operational semantics, based on a quasi term-rewriting system that specifies a completely deterministic evaluation strategy; a reduction semantics, based on lambda-calculus-like reduction relations that satisfy the Church-Rosser property; a denotational semantics, based on call-by-value continuation passing. We prove that these three semantics coincide on programs

Preuve de confluence de λexn\lambda_{exn}

Rapport interne.N.A

Proceedings of the ESSLLI-2000 Student Session

We draw attention to the fact that Barwise and Etchemendy's logic teaching program, Hyperproof, does not distinguish Visual Reasoning from CaseBased Reasoning. We indicate how this may be a problem when Hyperproof is used for cognitive research, and propose to solve the problem by using a similar system based on Peirce's Existential Graphs. We present a prototype of this system, called the EGG (Existential Graphs GUI)

Future needs and recommendations in the development of species sensitivity distributions: Estimating toxicity thresholds for aquatic ecological communities and assessing impacts of chemical exposures

A species sensitivity distribution (SSD) is a probability model of the variation of species sensitivities to a stressor, in particular chemical exposure. The SSD approach has been used as a decision support tool in environmental protection and management since the 1980s, and the ecotoxicological, statistical, and regulatory basis and applications continue to evolve. This article summarizes the findings of a 2014 workshop held by the European Centre for Toxicology and Ecotoxicology of Chemicals and the UK Environment Agency in Amsterdam, The Netherlands, on the ecological relevance, statistical basis, and regulatory applications of SSDs. An array of research recommendations categorized under the topical areas of use of SSDs, ecological considerations, guideline considerations, method development and validation, toxicity data, mechanistic understanding, and uncertainty were identified and prioritized. A rationale for the most critical research needs identified in the workshop is provided. The workshop reviewed the technical basis and historical development and application of SSDs, described approaches to estimating generic and scenario-specific SSD-based thresholds, evaluated utility and application of SSDs as diagnostic tools, and presented new statistical approaches to formulate SSDs. Collectively, these address many of the research needs to expand and improve their application. The highest priority work, from a pragmatic regulatory point of view, is to develop a guidance of best practices that could act as a basis for global harmonization and discussions regarding the SSD methodology and tools