> I have seen no data to backup this claim which would override my personal experience. I think that there are two reasons why good data on this is not forthc

> I have seen no data to backup this claim which would override my personal experience. I think that there are two reasons why good data on this is not forthcoming. The first is that for a long time the dominant statically typed languages have been C++, which forfeits most of the potential advantages of static typing by also being weakly typed, and Java, which handles types somewhat better (while by no means being state-of-the-art) but brings its own productivity challenges. The second is, the kinds of enormous long-lived maintained-by-50-full-timers hoary old enterprise applications that I think most fans of static typing have in mind when they say, "I wouldn't want to maintain that in a dynamic language!" aren't often written in dynamic languages. This in and of itself could be seen as evidence that dynamic languages really are unsuited to the task. Perhaps the more interesting evidence, though, is the tendency of what few larger- and longer-lived dynamic projects there are to become famous for messy code. This hits at what I think fans of static typing are really talking about - that doing any sort of large-scale refactor in a dynamic language is a terrifyingly error-prone experience. You need to rely on ever-fallible humans to have written tests that exercise all relevant code paths in order to verify that the refactor was successful in even the most basic terms. For someone who's used to having the compiler quickly, reliably and exhaustively provide the same feedback, having to fall back on the source of all known bugs (programmers) to do the same job leaves one feeling a bit exposed.