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Thanks to the author for sharing this. I do want to learn more about HKTs but I feel like this article is written for people who already know what HKTs are. It

• whatshisface 5y ago
  HKTs only stick out when you're in a rigidly structured programming environment where the compiler has to understand what you're writing. In old-fashioned static languages, the following is impossible, while in Python it's unremarkable: def class_closure(x): class A(object): def tell_me_x(self): return x return A Then, class_closure(7)().tell_me_x() => 7 This is just a weird pattern (with some rare uses) in Python, but in a strictly typed language, you're going to have to be able to express what the signature of class_closure is. In this case, it'd be something like, class_closure: Int -> Type The signature is a type that refers to, within itself, the concept of types. That makes it "higher-kinded." Before researchers got a grip on the theory surrounding this, you could only have either languages where that was impossible, or languages that gave up on static type checking entirely.
• azurelake 5y ago
  It's just a fancy way of saying you can use generics for the "outer" type of a container. e.g. List<T> vs. U<T>. That's literally all there is to it.