Khats, cats on higher-kinded amphets

This is a study on structures from Category Theory applied to higher-kinded structures.

For example:

type T[_[_], _]

val nat: F ~> G = ???

FunctorK[T].mapk(nat)

It provides a set of typeclasses for higher-kinded structures based on cats FunctionK/Natural Transformation and following the typeclass design imagined by Alois Cochard in Scato project and also used in Scalaz 8.0.x branch.

Do you wonder whether it's useful or just brainfucking?

I wonder too yet the brain effort is fun and I have a few interesting ideas in mind to dig and the code is still very experimental... Let's take it as an exercise of style until it becomes more (or not)!