Many developers who discover F# as their first functional language are amazed by features such as algebraic data types or immutability by default. However, this is not the end of what FP has to offer, but mere beginning.
In the talk I gave at F# Online Meetup, I presented more advanced concepts of functional programming through a library called FSharpPlus, which provides various features such as Lens/Optics module, Monads and other common FP abstractions.
I showcased example usages of those concepts in my recommendation system for recipes, so you can see their benefit in real project alongside with a whole sample application serving as a reference point.

Watch the recording and check my slides.
Also, feel free to go through two apps – sample & older but real app.