After many years using OOP, the switch to Functional world is not an easy one. On his experience teaching Functional Programming to senior OOP developers, Uberto will show some of the key concepts that you need to "unlearn" to use effectively the functional paradigm. Uberto will also introduce a pragmatical approach to Functional Design, where pragmatical “concerned with actual occurrences” and not just monads for the sake of monads. We will look at a concrete example of how to switch from a OO design to a real Functional one. All the examples are in Kotlin.