In this part, we’ll widen our focus to designing entire applications or tackling cross-cutting concerns with a functional approach.
Chapter 9 shows how you can modularize and compose an application with functions only, using techniques like partial application and the powerful Aggregate function (fold).
Chapter 10 discusses another core function, Apply. It also teaches you about implementing the LINQ query pattern and compares some functional patterns like applicatives and monads. Chapter 10 also introduces a technique called property-based testing, which verifies that your code observes certain properties by throwing random data at it.