Have you ever wondered how Julia dispatches method calls? As an answer, have you been pointed to a mysterious .c file in the source tree understood by at most five people on Earth? Are you afraid of complex type annotations? If yes, do not wonder anymore. This talk will be a friendly walkthrough across the rules that govern subtyping, the relation at the very core of method dispatch. We will start from the basics and we will build intuitions to grasp the intricate but unavoidable interactions between the various features of Julia type system. As a result you won’t be afraid to rely on the most advanced features of Julia type system anymore, and won’t be puzzled by runtime error messages or odd dispatch behaviors ever again.
