it's desperate desire to turn Scala into Haskell ends up turning an awesome ML-inspired language into a vastly inferior religious (...ahem, pure) language. But Cats and Shapeless aren't Scalaz.

I claim that from a technical perspective they are more or less equivalent and they only forked due to a feud. So if you want to avoid Haskell-inspired constructs in Scalaz, Cats won't be much to your liking either.

Glad we are on the same page!