simple and readable,  because reuse of algorithms requires a readable expression of the ideas, but also because CLAIRE was part of a research and teaching project and we needed an executable pseudo-code to demonstrate algorithms;

 multi-paradigm (supporting logic, imperative and functional programming styles), with few simple and well-understood concepts, such as objects, functions, rules and versioning for building search trees;

compiled efficiently so that using a high-level language is no longer a burden when writing algorithms that will compete against C++ or FORTRAN implementations.