Ruby is a dynamically typed language. This means, generally speaking, that objects have types, but variables don’t. While this makes for a very easy-to-use programming language, it also means that there isn’t any way for the language to know, or enforce, types when they are passed to operators or methods. It has been proposed that Ruby 3 will include a “soft typing” system, letting developers include optional typing on their variables. In this talk, John Cinnamond demonstrates the use, and implementation, of a soft-typing system in an extremely simple language. If you’re curious about the future of typing in Ruby, or of how type systems are implemented, you’ll enjoy this talk.