The only one I know of that can do both typed and untyped readily (without weird third-party libraries) is Racket v. Typed Racket. It would actually be interes

The only one I know of that can do both typed and untyped readily (without weird third-party libraries) is Racket v. Typed Racket. It would actually be interesting to see a study done comparing the two, but the sometimes shaky documentation of the latter might even throw the results.