Any reason why existing typecheckers for Ruby didn't make the cut? There are projects like RDL [1] which provide similar functionality. I know for certain that people from Stripe were taking a look at it last year from the issues they had raised.
Disclosure: I am a grad student, recently started working on RDL.
Disclosure: I am a grad student, recently started working on RDL.
[1]: https://github.com/plum-umd/rdl