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Declarative multi-paradigm languages combine the most important features of functional , logic and concurrent programming. The computational model of such integrated languages is usually based on a combination of two different operational principles: narrowing and residuation. This work is motivated by the fact that a precise definition of an operational(More)
One of the key features of the integration of functional and logic languages is the access to non-deterministic computations from the functional part of the program. In order to ensure the determinism of top-level computations in a functional logic program, which is usually a monadic sequence of I/O operations, one has to encapsulate the non-determinism(More)
In this article we use model checking techniques to debug Concurrent Haskell programs. LTL formulas specifying assertions or other properties are verified at run-time. If a run which falsifies a formula is detected, the debugger emits a warning and records the path leading to the violation. It is possible to dynamically add formulas at runtime, giving a(More)
Assertions test expected properties of run-time values without disrupting the normal computation of a program. We present a library for enriching Haskell programs with assertions. Expected properties can be specified in a parser-combinator like language. The assertions are lazy: they do not force evaluation but only examine what is evaluated by the program.(More)
The DARPA Agent Markup Language ontology for Services (DAML-S) enables the description of Web-based services, such that they can be discovered, accessed and composed dynamically by intelligent software agents and other Web services, thereby facilitating the coordination between distributed, heterogeneous systems on the Web. We propose a formalised syntax(More)
We introduce the theoretical basis for tracing lazy functional logic computations in a declarative multi-paradigm language like Curry. Tracing computations is a difficult task due to the subtleties of the underlying operational semantics which combines laziness and non-determinism. In this work, we define an instrumented operational semantics that generates(More)
The DARPA Agent Markup Language ontology for Services (DAML-S) enables the description of Web-based services, such that they can be discovered, accessed and composed dynamically by intelligent software agents and other Web services, thereby facilitating the coordination between distributed, heterogeneous systems on the Web. We propose a formalised syntax(More)