Mário Florido

CLP(Flex): Constraint Logic Programming Applied to XML Processing

In this paper we present an implementation of a constraint solving module, CLP(Flex), for dealing with unification in an equality theory for terms with flexible arity function symbols. Then we present an application of CLP(Flex) to XML-processing where XML documents are abstracted by terms with flexible arity symbols. This gives a highly declarative model for XML processing yielding a substantial degree of flexibility in programming.

XCentric: logic programming for XML processing

Here we present the logic-programming language XCentric, discuss design issues, and show its adequacy for XML processing. Distinctive features of XCentric are a powerful unification algorithm for terms with functors of arbitrary arity (which correspond closely to XML documents) and a rich type language that uses operators such as repetition (*), alternation, etc, as types allowing a compact representation of terms with functors with an arbitrary number of arguments (closely related to standard type languages for XML). This new form of unification together with an appropriate use of types yields a substantial degree of flexibility in programming.

VeriFLog: a constraint logic programming approach to verification of website content

Web site semantic content verification can be a tedious and error prone task. In this paper we propose a framework for syntactic validation and semantic verification based on the logic programming language XCentric. The high declarative model of this language based on a new unification algorithm along with an interface to semistructured data provides an elegant framework for semantic error detection. The result is an easy to follow model to improve website quality and management.

Automatic amortised analysis of dynamic memory allocation for lazy functional programs

This paper describes the first successful attempt, of which we are aware, to define an automatic, type-based static analysis of resource bounds for lazy functional programs. Our analysis uses the automatic amortisation approach developed by Hofmann and Jost, which was previously restricted to eager evaluation. In this paper, we extend this work to a lazy setting by capturing the costs of unevaluated expressions in type annotations and by amortising the payment of these costs using a notion of lazy potential. We present our analysis as a proof system for predicting heap allocations of a minimal functional language (including higher-order functions and recursive data types) and define a formal cost model based on Launchburys natural semantics for lazy evaluation. We prove the soundness of our analysis with respect to the cost model. Our approach is illustrated by a number of representative and non-trivial examples that have been analysed using a prototype implementation of our analysis.

Type-Based Static and Dynamic Website Verification

Maintaining large Web sites and verifying their semantic content is a difficult task. In this paper we propose a framework for syntactic validation, semantic verification and automatic correction of Web sites based on the logic programming language XCentric. Here we purpose a new approach conciliating the highly declarative model of XCentric with compile and run time verification techniques, mainly based on type checking to automatically repair and audit Web sites. The result is an easy to follow model to improve and audit Web site content.

The power of linear functions

The linear lambda calculus is very weak in terms of expressive power: in particular, all functions terminate in linear time. In this paper we consider a simple extension with Booleans, natural numbers and a linear iterator. We show properties of this linear version of Godel’s System

Type-Based XML Processing in Logic Programming

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Type-Based Allocation Analysis for Co-recursion in Lazy Functional Languages

and study the class of functions that can be represented. Surprisingly, this linear calculus is extremely expressive: it is as powerful as System

PrologCheck – Property-Based Testing in Prolog

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