An empirical study of the influence of static type systems on the usability of undocumented software

Although the study of static and dynamic type systems plays a major role in research, relatively little is known about the impact of type systems on software development. Perhaps one of the more common arguments for static type sys-tems in languages such as Java or C++ is that they require developers to annotate their code with type names, which is thus claimed to improve the documentation of software. In contrast, one common argument against static type sys-tems is that they decrease flexibility, which may make them harder to use. While these arguments are found in the liter-ature, rigorous empirical evidence is lacking. We report on a controlled experiment where 27 subjects performed pro-gramming tasks on an undocumented API with a static type system (requiring type annotations) as well as a dynamic type system (which does not). Our results show that for some tasks, programmers had faster completion times using a static type system, while for others, the opposite held. We conduct an exploratory study to try and theorize why