The second link in particular is quite an in-depth look at the more theoretical side of functional programming but in the first part it deals with fundamentals, and is not super complex to follow.
I say this as someone who can grasp the basics like functional composition, currying, partial application etc. but not stuff like monads, functors, etc. so take my advice for what it's worth :)
Two resources I can recommend are:
- http://reactivex.io/learnrx/
- https://github.com/MostlyAdequate/mostly-adequate-guide
The second link in particular is quite an in-depth look at the more theoretical side of functional programming but in the first part it deals with fundamentals, and is not super complex to follow.
I say this as someone who can grasp the basics like functional composition, currying, partial application etc. but not stuff like monads, functors, etc. so take my advice for what it's worth :)
Good luck!