RUTILS is my take on the Lisp "modernization" effort that adds the missing syntactic and data structure pieces, which became proven and well-established, in Lisp itself or in other languages. The programming field is constantly developing while the Lisp standard remains fixed so some additions, over time, are not only desirable but inevitable, if we don't want to lag behind. Thankfully, Lisp provides all the necessary means for implementing them and so, with some creativity, there's a way to have access to almost anything you want and need while retaining full backward compatibility (a lack of which is the most critical problem of some alternative solutions).
I, surely, understand that using such an extension remains a matter of taste and not every Lisper will like it. I didn't try to seriously promote it and was quite satisfied with the benefit that it provided to me and my teams' development. However, as I decided to use it for the "Programming Algorithms" book, it received some attention and a number of questions. From the direction of the discussions, I realized that the docs are lacking a critical part — the tutorial explaining how to effectively use the library. This text is intended to bridge that gap. I had to finish it before publishing the next chapter of the book, which I'll do on Friday.
So, today, version 5 of RUTILS is released alongside with the tutorial that aims to better explain its usage.