Integrating multiple APIs of different sorts (e.g. Web facing RESTful, internal library, data storage, low level event logging, etc.) into a single application, the complexity of the manifold interactions can very quickly become an obstacle to agility. In this session, engineers from Versal will discuss how their move to a functional programming model allowed them to migrate from an event-sourced architecture and in-memory hierarchical data model to an on-disk relational data model that allowed them to greatly simplify their application development process. Examples of how to apply functional programming concepts to various API designs will be provided.