I'm testing that and Sorbet is very far from being a nice experience right now. Tooling is somewhat broken. srb rbi gems often marks gems as typed ignore, which in turns makes constants unavailable.

My biggest problem is that it's not possible to represent "duck typing" (structural typing), which is core to ruby. So an object that is "callable" (a lambda with no args, a block with no args or an object with call and no args) cannot be represented, since the expectation is that the object includes some interface (module), not that it has a method #call