You can test it out yourself: http://docs.racket-lang.org/ts-guide/ http://docs.racket-lang.org/ts-guide/ Typed Racket lets you easily migrate portions (or the

You can test it out yourself: http://docs.racket-lang.org/ts-guide/ http://docs.racket-lang.org/ts-guide/ Typed Racket lets you easily migrate portions (or the entirety) of a dynamically typed codebase into an equivalent statically-typed version. You get the best of both - easy prototyping with dynamic typing, robustness and scalability of static typing, and then the flexibility of applying those choices to parts of your codebase while keeping everything completely interoperable.