I see some crazy/weird critics in the world. I’ll skip the details, but yes, Functional Programming, Simplified is for beginners who are new to functional programming (FP). I wrote it because I thought many other current FP books were too hard to read, and I wasted a lot of my own time with those poorly-written resources. (Frankly, when I see that something is poorly written it makes me think that the author either doesn’t care about his readers, or doesn’t understand the subject well enough to explain it well.)
I guess I could have named my book Functional Programming in Scala for Beginners, but the key thing for me is that if you want more people to learn FP — which should be a positive thing — you need to break it down into smaller components, as I have done. The book isn’t perfect, and I hope the next edition is better, but it seems to be helping a lot of people, so I’m happy about that.