If you want to learn FP for the sake of learning FP:
Learn you a Haskell is a great start.
Now, something to know about my opinion:
- I think Haskell is great.
- I think Haskell's tooling is pretty doodoo.
So, you could use Haskell Playground or something like repl.it to run Haskell in your browser. This should save you on a confusing setup.