Constraints for Free in Concurrent Computation

We investigate concurrency as unifying computational paradigm which integrates functional, constraint, and object-oriented programming. We propose the-calculus as a uniform foundation of concurrent computation and formally relate it to other models: The-calculus with equational constraints provides for logic variables and is bisimilar to the-calculus. The-calculus without constraints is a proper subset of the-calculus. We prove its Turing completeness by embedding the eager-calculus in continuation passing style. The-calculus over an arbitrary constraint system is an extension of the standard cc-model with procedural abstraction.