TypeProf: A type analysis tool for Ruby code based on abstract interpretation Synopsis gem install typeprof typeprof app.rb Demo # test.rb def foo(x) if x > 10 x.to_s else nil end end foo(42) $ typeprof test.rb # Classes class Object def foo : (Integer) -> String? end Documentation English / 日本語 Playground You can try typeprof gem on the Web via the URL below. https://mame.github.io/typeprof-playground/