[ReleaseCandidat]

Higher (-order) kinded types describe functions on type constructors. Type constructors are "generic types", like `T[]` that generate a list from a single type `T` or like `Map<S, T>` that generates a new type from two types `S` and `T`. A higher kinded type constructor is one, where you could use any (well, with certain prerequisites) of these type constructors to generate a new type. Let's say you want to have a function `map` (like `Array.map`) that works not only with `T[]` but also with `Tree<T>`, `Maybe<T>` (`= T | undefined`), ... HKT give you the possibility to write the type of such type functions.