I wrote a book, and it is finally here! And it is a book about something nobody ever written, even when thousands of people use these things every day. Higher Order Functions - these are functions that either accept functions as parameters, or return functions, or both. They are extremely powerful form of abstraction, that replace not only most of design patterns, but also can simplifty algorithms. This is the core focus of my book. On hundred or so of algorithms I am showing, how HOFs can make many algorithms (I picked ones from operations research, but the lesson is universal) easier to update, reason about, and reuse. If you are a curious developer or SW architect, who wants to dramatically simplify your algorithms while making them more universal, without sacrificing performance, this is a book for you. In 3 weeks from now, you will be able to order it.