This document discusses using Scala and functional programming concepts like the cake pattern and validation in Goozy, a social networking application. It describes how Goozy's API uses Scala for its performance, conciseness and advanced object-oriented features. It also discusses issues with using Lift and how the cake pattern improved organization by encapsulating dependencies. Validation is implemented using Scalaz to catch errors and exceptions are converted to a common error type for reporting. In summary, functional programming brought organization and error handling benefits but also increased complexity compared to exceptions.