It may sound naive, but is there any programming language, or research thereof, based entirely on category theory?

I mean this as opposed to embedding CT concepts as an additional feature (like for Haskell or scala).

Would it be too abstract or too complex as an approach, or are there any known reasons that makes it impossible or impractical?

I have only a relative understanding of the theory as related to programming, so please give me some explanation if the question doesn't makes sense at all