Comment by Milner08

Im a Scala fan, so all these will be focused around Scala, but they will teach you about Monad and Category Theory.

I would start with http://learnyouahaskell.com - Its Haskell based but it covers them pretty well.

Otherwise I use https://typelevel.org/cats/ for Scala daily and they have an _ok_ guide. But the best guide I've found for it was http://eed3si9n.com/herding-cats/