Treffer: CleanJava: A formal notation for functional program verification

—Unlike Hoare-style program verification, functional program verification supports forward reasoning by viewing a program as a mathematical function from one program state to another and proving its correctness by essentially comparing two mathematical functions, the function computed by the program and its specification. Since it requires a minimal mathematical background and reflects the way programmers reason about the correctness of a program informally, it can be taught and practiced effectively. However, there is no formal notation supporting the functional program verification. In this paper, we propose a formal notation for writing functional program specifications for Java programs. The notation, called CleanJava, is based on the Java expression syntax and is extended with a mathematical toolkit consisting of sets and sequences. The vo-cabulary of CleanJava can also be enriched by introducing user-