TOY: A System for Experimenting with Cooperation of Constraint Domains

AbstractThis paper presents, from a user point-of-view, the mechanism of cooperation between constraint domains that is currently part of the system TOY, an implementation of a constraint functional logic programming scheme. This implementation follows a cooperative goal solving calculus based on lazy narrowing. It manages the invocation of solvers for each domain, and projection operations for converting constraints into mate domains via mediatorial constraints. We implemented the cooperation among Herbrand, real arithmetic (R), finite domain (FD) and set (S) domains. We provide two mediatorial constraints: The first one relates the numeric domains FD and R, and the second one relates FD and S

Constraint Functional Logic Programming over Finite Domains.

Abstract In this paper, we present our proposal to Constraint Functional Logic Programming over Finite Domains (CFLP (FD) ) with a lazy functional logic programming language which seamlessly embodies finite domain (FD) constraints. This proposal increases the expressiveness and power of constraint logic programming over finite domains (CLP (FD) ) by combining functional and relational notation, curried expressions, higher-order functions, patterns, partial applications, non-determinism, lazy evaluation, logical variables, types, domain variables, constraint composition, and finite domain constraints. We describe the syntax of the language, its type discipline, and its declarative and operational semantics. We also describe TOY(FD), an implementation for CFLP (FD) , and a comparison of our approach with respect to CLP (FD) from a programming point of view, showing the new features we introduce. And, finally, we show a performance analysis which demonstrates that our implementation is competitive with respect to existing CLP (FD) systems and that clearly outperforms the closer approach to CFLP (FD)

A Concurrent Operational Semantics for Constraint Functional Logic Programming

In this paper we describe a sound and complete concurrent operational semantics for constraint functional logic programming languages which allows to model declarative applications in which the interaction between demand-driven narrowing and constraint solving helps to prune the search space, leading to shorter goal derivations. We encode concurrency into the generic CFLP(D) scheme, a uniform foundation for the operational semantics of constraint functional logic programming systems parameterized by a constraint solver over the given domain D. In this concurrent version of the CFLP(D) scheme, goal solving processes can be executed concurrently and cooperate together to perform their specific tasks via demand-driven narrowing and declarative residuation guided by constrained definitional trees, constraint solving, and communication by synchronization on logical variables