DRAFT (31/08/2004) The Syntax, Semantics, and Type System of esra

Current-generation constraint programming languages are considered by many, especially in industry, to be too low-level, difficult, and large. We argue that solver-independent, high-level relational constraint modelling leads to a simpler and smaller language, to more concise, intuitive, and analysable models, as well as to more efficient and effective model formulation, maintenance, reformulation, and verification. All this can be achieved without sacrificing the possibility of efficient solving, so that even time-pressed or less competent modellers can be well assisted. Towards this, we propose the esra relational constraint modelling language, showcase its elegance on some well-known problems, and outline a compilation philosophy for such languages.