Depends on the problem. As a user if both Haskell and various LISPs since 1990, I would say I personally am as productive in both strongly typed and dynamicall

Depends on the problem. As a user if both Haskell and various LISPs since 1990, I would say I personally am as productive in both strongly typed and dynamically typed languages, assuming I have a match between my problem and my platform, and avoid overengineering my types (heh). I am also equally productive in what I consider weakly typed languages (hello, Java), when I can avoid boilerplate hell. Bottom line is I think the productivity of the developer is more a function of the familiarity with the language, platform, tooling and problem (and proposed solution) than how strongly typed the language is. I do find that having a REPL improves productivity in essentially all cases.