No Arabic abstract
Paisley is an extensible lightweight embedded domain-specific language for nondeterministic pattern matching in Java. Using simple APIs and programming idioms, it brings the power of functional-logic processing of arbitrary data objects to the Java platform, without constraining the underlying object-oriented semantics. Here we present an extension to the Paisley framework that adds pattern-based control flow. It exploits recent additions to the Java language, namely functional interfaces and lambda expressions, for an explicit and transparent continuation-passing style approach to control. We evaluate the practical impact of the novel features on a real-world case study that reengineers a third-party open-source project to use Paisley in place of conventional object-oriented data query idioms. We find the approach viable for incremental refactoring of legacy code, with significant qualitative improvements regarding separation of concerns, clarity and intentionality, thus making for easier code understanding, testing and debugging.
The possibility of translating logic programs into functional ones has long been a subject of investigation. Common to the many approaches is that the original logic program, in order to be translated, needs to be well-moded and this has led to the common understanding that these programs can be considered to be the ``functional part of logic programs. As a consequence of this it has become widely accepted that ``complex logical variables, the possibility of a dynamic selection rule, and general properties of non-well-moded programs are exclusive features of logic programs. This is not quite true, as some of these features are naturally found in lazy functional languages. We readdress the old question of what features are exclusive to the logic programming paradigm by defining a simple translation applicable to a wider range of logic programs, and demonstrate that the current circumscription is unreasonably restrictive.
While modern software development heavily uses versioned packages, programming languages rarely support the concept
We develop formal foundations for notions and mechanisms needed to support service-oriented computing. Our work builds on recent theoretical advancements in the algebraic structures that capture the way services are orchestrated and in the processes that formalize the discovery and binding of services to given client applications by means of logical representations of required and provided services. We show how the denotational and the operational semantics specific to conventional logic programming can be generalized using the theory of institutions to address both static and dynamic aspects of service-oriented computing. Our results rely upon a strong analogy between the discovery of a service that can be bound to an application and the search for a clause that can be used for computing an answer to a query; they explore the manner in which requests for external services can be described as service queries, and explain how the computation of their answers can be performed through service-oriented derivatives of unification and resolution, which characterize the binding of services and the reconfiguration of applications.
Object-oriented programming (OOP) is aimed at describing the structure and behaviour of objects by hiding the mechanism of their representation and access in primitive references. In this article we describe an approach, called concept-oriented programming (COP), which focuses on modelling references assuming that they also possess application-specific structure and behaviour accounting for a great deal or even most of the overall program complexity. References in COP are completely legalized and get the same status as objects while the functions are distributed among both objects and references. In order to support this design we introduce a new programming construct, called concept, which generalizes conventional classes and concept inclusion relation generalizing class inheritance. The main advantage of COP is that it allows programmers to describe two sides of any program: explicitly used functions of objects and intermediate functionality of references having cross-cutting nature and executed implicitly behind the scenes during object access.
Software testing is one of the most popular validation techniques in the software industry. Surprisingly, we can only find a few approaches to testing in the context of logic programming. In this paper, we introduce a systematic approach for dynamic testing that combines both concrete and symbolic execution. Our approach is fully automatic and guarantees full path coverage when it terminates. We prove some basic properties of our technique and illustrate its practical usefulness through a prototype implementation.