Awful stuff. These principles could only ever make sense in a dynamic language since it's mostly manually enforcing some of the basic functionality of a type system, but the fact that he also tries to argue this style could be used in a language like C# throws that defense out the window.
https://blog.klipse.tech/databook/2022/06/22/generic-data-st...
The examples also contradict his other principles, i.e. immutability.