S3L : a Fair Functional Language Implementing Infinite Sets

S3L/sup 1/ is a functional language, that allows easy manipulation of sets. Sets provide a better expressive power in many problems. Often, sets are modelled by lists, and predicates on sets are defined using implicit order over lists. In contrast, in S3L, sets are native objects. They can be finite or infinite, and for an efficient implementation multiple occurences of the same object are allowed. We describe, in the paper, the main features of the language, followed by a discussion on infinite sets. This leads us to deal with fairness, and tools expressing it, using a denotational approach.