In this chapter, we started discussing the importance of organizing source code for larger applications. We explored in detail how to establish namespaces and how to implement them using modules and submodules. To manage package dependencies, we introduced the concept of semantic versioning and learned how to use it properly with Julia's package manager.
Then, we went over the details of how to design an abstract type hierarchy and define functions for abstract types. We also discussed concrete types and the concepts of immutability and mutability. We demonstrated how to use union types when working with data types from different abstract type hierarchies. We looked at two common operators (isa and is-a-subtype-of) for data types. To further reuse data types, we introduced parametric types and looked at how they apply to both concrete types and abstract types.
Finally...
