How about a simple functional programming book written with this style:
No category theory.
Just some Java & Scala code.
Robert Martin’s tweet about writing a new simple functional programming book (in Clojure) was shared with me here, and I like his initial wording on not worrying about monads, monoids, functors, and category theory.
I said almost the exact same thing five years in the beginning of my book, Functional Programming, Simplified, and then in Learn Functional Programming Without Fear I show how to start with Java/OOP code and slowly transition to a functional programming style with Scala/FP examples. Both books focus on pragmatic functional programming source code examples, without getting lost in FP theory.