Our game works like a charm, but there is one thing we can improve—storing our article info as a Dict. Julia's dictionaries are very flexible and powerful, but they are not a good fit in every case. The Dict is a generic data structure that is optimized for search, delete, and insert operations. None of these are needed here—our articles have a fixed structure and contain data that doesn't change once created. It's a perfect use case for objects and object-oriented programming (OOP). Looks like it's time to learn about types.
Julia's type system is the bread and butter of the language—it is all-pervasive, defining the language's syntax and being the driving force behind Julia's performance and flexibility. Julia's type system is dynamic, meaning that nothing is known about types until runtime, when the actual values manipulated by the program are available. However, we can benefit from the advantages of static typing by using type annotations—indicating...