Expressive Modes and Species of Language

Computer languages are usually lumped together into broad 'Paradigms', leaving one in want of a finer classification of kinds of languages. Theories distinguishing between 'Genuine differences' in language have been called for, and the authors propose that such differences can be observed through a notion of expressive mode. They outline this concept, propose how it could be operationalized and indicate a possible context for the development of a corresponding theory. Finally they consider a possible application in connection with evaluation of language revision. They illustrate this with a case, investigating possible revisions of the relational algebra in order to overcome weaknesses of the division operator in connection with universal queries.