Functional programming is very powerful as it leads to very terse programs with high-quality and low number of faults. This is because good functional code doesn't have any side effects—a place where most of the imperative object-oriented code has its bugs.

In this chapter, we've been looking at functional concepts that make it easier to write good code that doesn't cause side effects and has a low number of bugs, but also code that is easier to test.

The next chapter we'll reach into the toolset that exists for programs written in F# and what it takes to get started with functional testing.