Constraint logic programming languages are an extension of logic programming languages where unification has been replaced by constraint solving. Constraint solving techniques allow to reduce the search space of a logic program dramatically and have been shown to be useful in a wide area of application domains. Functional-logic languages are a different branch in the group of declarative languages, which combine the reduction of expressions with unification. In contrast to purely functional languages, functional-logic languages allow for computations with partially known data and offer built-in search strategies, allowing for a more concise formulation of programs. Compared to purely logic languages, functional-logic languages provide functions and a declarative approach to I/O, thus avoiding the need for non-declarative language constructs (e.g. the ubiquitous cut in Prolog). In this paper we will consider the integration of constraint programming and functional-logic programming in the context of the language Curry. Curry is a multi-paradigm declarative language, which aims at unifying the different lines of research in functional-logic programming. In particular, we have chosen the domain of linear constraints over real numbers and will describe the semantic and operational issues of this integration.
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