DAReing to reduce the annotation overheads of verified programs

Modern program verifiers use the same uniform program text to both specify and implement programs. The program text is also used to provide the necessary guidance to ensure that the program satisfies its specification. The amount of guidance required is often called the annotation overhead. This can be high and is often seen as a hindrance for wider use of program verifiers, as development time is increased and the guidance may obfuscate the program text. In this paper we introduce the DARe tool, which automatically removes as much unnecessary guidance as possible for the Dafny program verifier. The tool is integrated with the Dafny IDE. To evaluate DARe, we apply it to 252 programs from the Dafny library and analyse the degree to which it is able to remove unnecessary guidance. Our results are very encouraging as a staggering 88% of the guidance can be removed.