This chapter discusses several organizational techniques for developing large-scale applications. Believe it or not, this is often something that is easily overlooked. When developing applications, we typically focus on building data types, functions, control flows, and so on. It is equally important, however, to organize the code properly so that it is clean and maintainable.

In the later part of this chapter, we will introduce Julia's type system. Data types are the most fundamental building blocks of any application. Julia's type system is one of its strongest features when compared to other programming languages. A solid understanding of the type system will enable us to achieve better designs.

The following topics will be covered in this chapter:

• The growing pains of developing applications
• Working with namespaces, modules, and packages
• Managing package dependencies
• Designing abstract types and concrete types
• Understanding parametric types
• Converting between data types

By the end of the chapter, you should know how to create your own packages, divide code into separate modules, and start creating new data types for your application.

Let's go!