Models help us make complex domains manageable in software. We don't map reality itself, but rather a reduced version: one that's powerful enough to create value. But how do we build such models? In Java, object orientation is often the first choice, since many widely used frameworks embrace and promote this paradigm.
Over the years, however, Java has gained many functional features that allow us to leverage the strengths of functional approaches for domain modeling.
Using an example, we'll explore how to express functional models of our business domains in code using modern Java features. This gives us another powerful tool in our toolbox, one that helps us not only design new systems with more value but also gradually regain control over legacy systems.
