alt Hacker NewsThere's an official format for defining types in separate files (RBS) and some tooling to type check them (matz doesn't like types next to the source code).
There's a pretty battle tested tool to define inline types as ruby syntax and type check both statically and at runtime[0].
It's still not a particularly nice situation imvho compared to typescript or python, but there's been some movement, and there's a newsletter that follows static typing developments [1] which may give you some insights.
I’ve used Sorbet on a project for 2 years recently and it honestly was the final nail in the coffin for Ruby for me.
Really rough around the edges, lots of stubs have to be added because support for gems is lackluster but whatever Sorbet generates are hit or miss etc. So you end up writing a lot of hard to understand annotations and/or people get frustrated and try to skip them etc.
Overall a very bad DX, compared to even typed Python. Don’t even want to compare it to TS because then it becomes really unfair.