In the previous chapter, we learned the various aspects of setting up the development environment wherein we covered the structure of a Scala project and identified the use of sbt for building and running projects. We covered REPL, which is a command-line interface for running Scala code, and how to develop and run code over the IDEA IDE. Finally, we implemented interactions with our simple chatbot application.

In this chapter, we will explore the so-called 'OO' part of Scala, which allows us to build constructions similar to analogs in any mainstream language, such as Java or C++. The object-oriented part of Scala will cover classes and objects, traits, pattern matching, case class, and so on. Finally, we will implement the object-oriented concepts that we learn to our chatbot application.

Looking at the history of programming paradigms, we will notice that the first generation of high-level programming languages (Fortran, C, Pascal) were procedure oriented...