Strictness analysis using abstract reduction

In this paper we present a new and general strictness analysis technique for lazy functional languages. In contrast to many other methods, this method is practically usable. This is shown with results of a real implementation. The key idea is the use of an abstract domain of which the elements rep resent various kinds of sets of concrete values. Reduction as well aa pattern matching in the abstract domain mimics reduction and pattern matching in the concrete domain in a very natural way. With th~ abstract domain various kinds of strictness analysis are possible. In particular, higher order functions and general data types (tuples and lists, but also user defined data types) fit perfectly well in this mechanism. In contrast to methods based on abstract interpretation, the abstract domain is infinite. Recursive functions are handled by a technique called reduction path analysis, Complicated and expensive fixed point derivation techniques are not needed. The implementation in the Concurrent Clean system shows that the analyser is very fast and that it finds much strictness information.