Implementing a purely functional domain model means we reap the benefits of functional programming at the heart of software to reduce complexity, improve communication, and enable change. What’s left outside, at the boundaries of our system, is mostly business-decision-free code that deals with side effects. As it turns out, event sourcing is a natural fit for such an approach.

In this talk, Jakub will introduce the benefits of a functional domain model, show examples of a domain that’s modelled with event sourcing, and explore the simplicity of testing such models.