Uncle Bob reviews the book Functional Programming for the Object Oriented Programmer:
We need something to bridge the gap between the huge population of OO programmers, and the growing need for functional programmers.
And continues about functional programming in general:
you’ll also learn a lot about OO that you may not have known before.
I could not agree more. When I discovered LISP ten years ago, I realized two things. First, there is much, much more to discover in programming than we Algol 60 programmer would think. Second, this holds especially for object oriented programming. The C++/Java point of view is just one way to apply OO.
Stop hesitating and tip a toe into functional programming.