It's also very worth looking at Typed Racket and Racket's contracts system! [1] http://docs.racket-lang.org/ts-guide/ [2] http://docs.racket-lang.org/g

It's also very worth looking at Typed Racket and Racket's contracts system! [1] http://docs.racket-lang.org/ts-guide/ [2] http://docs.racket-lang.org/guide/contracts.html?q=contracts