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Publications

Publications by Luís Soares Barbosa

2007

Higher-order lazy functional slicing

Authors
Rodrigues, NF; Barbosa, LS;

Publication
JOURNAL OF UNIVERSAL COMPUTER SCIENCE

Abstract
Program slicing is a well known family of techniques intended to identify and isolate code fragments which depend on, or are depended upon, specific program entities. This is particularly useful in the areas of reverse engineering, program understanding, testing and software maintenance. Most slicing methods, and corresponding tools, target either the imperative or the object oriented paradigms, where program slices are computed with respect to a variable or a program statement. Taking a complementary point of view, this paper focuses on the slicing of higher-order functional programs under a lazy evaluation strategy. A prototype of a Haskell slicer, built as proof-of-concept for these ideas, is also introduced.

2006

Generic process algebra: A programming challenge

Authors
Ribeiro, PR; Barbosa, MA; Barbosa, LS;

Publication
JOURNAL OF UNIVERSAL COMPUTER SCIENCE

Abstract
Emerging interaction paradigms, such as service-oriented computing, and new technological challenges, such as exogenous component coordination, suggest new roles and application areas for process algebras. This, however, entails the need for more generic and adaptable approaches to their design. For example, some applications may require similar programming constructs coexisting with different interaction disciplines. In such a context, this paper pursues a research programme on a coinductive rephrasal of classic process algebra, proposing a clear separation between structural aspects and interaction disciplines. A particular emphasis is put on the study of interruption combinators defined by natural co-recursion. The paper also illustrates the verification of their properties in an equational and pointfree reasoning style as well as their direct encoding in Haskell.

2006

Program slicing by calculation

Authors
Rodrigues, NF; Barbosa, LS;

Publication
JOURNAL OF UNIVERSAL COMPUTER SCIENCE

Abstract
Program slicing is a well known family of techniques used to identify code fragments which depend on or are depended upon specific program entities. They are particularly useful in the areas of reverse engineering, program understanding, testing and software maintenance. Most slicing methods, usually oriented towards the imperative or object paradigms, are based on some sort of graph structure representing program dependencies. Slicing techniques amount, therefore, to ( sophisticated) graph transversal algorithms. This paper proposes a completely different approach to the slicing problem for functional programs. Instead of extracting program information to build an underlying dependencies' structure, we resort to standard program calculation strategies, based on the so-called Bird-Meertens formalism. The slicing criterion is specified either as a projection or a hiding function which, once composed with the original program, leads to the identification of the intended slice. Going through a number of examples, the paper suggests this approach may be an interesting, even if not completely general, alternative to slicing functional programs.

2003

Towards a calculus of state-based software components

Authors
Barbosa, LS;

Publication
JOURNAL OF UNIVERSAL COMPUTER SCIENCE

Abstract
This paper introduces a calculus of state-based software components modelled as concrete coalgebras for some Set endofunctors, with specified initial conditions. The calculus is parametrized by a notion of behaviour, introduced as a strong ( usually commutative) monad. The proposed component model and calculus are illustrated through the characterisation of a particular class of components, classified as separable, which includes the ones arising in the so-called model oriented approach to systems' design.

2004

A relational model for component interconnection

Authors
Barbosa, MA; Barbosa, LS;

Publication
JOURNAL OF UNIVERSAL COMPUTER SCIENCE

Abstract
The basic motivation of component based development is to replace conventional programming by the composition of reusable off-the-shelf units, externally coordinated through a network of connecting devices, to achieve a common goal. This paper introduces a new relational model for software connectors and discusses some preliminary work on its implementation in Haskell. The proposed model adopts a coordination point of view in order to deal with components' temporal and spatial decoupling and, therefore, to provide support for looser levels of inter-component dependency and effective external control.

2008

A relational model for confined separation logic

Authors
Wang, SL; Barbosa, LS; Oliveira, JN;

Publication
TASE 2008: SECOND IFIP/IEEE INTERNATIONAL SYMPOSIUM ON THEORETICAL ASPECTS OF SOFTWARE ENGINEERING, PROCEEDINGS

Abstract
Confined separation logic is a new extension to separation logic designed to deal with problems involving dangling references within shared mutable structures. In particular it allows for reasoning about confinement in object-oriented programs. In this paper, we discuss the semantics of such an extension by defining a relational model for the overall logic, parametric on the shapes of both the store and the heap. This model provides a simple and elegant interpretation of the new confinement connectives and helps in seeking for duals. A number of properties of this logic are proved calculationally.

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