I remember writing Rust in university a year before this was published. How far the language has come since then! The title should be updated to include the date.<p>The first koan strikes me as a timeless lesson about the advantages of the borrow checker. I came out of it feeling as if I had learned something, though it was really what I knew all along: it was one of the reasons I wrote rust.<p>The second felt tired. Of course OOP limits us to only objects!<p>The third I can see as a larger story about programming. As it applies to Rust? Perhaps it is saying that it is OK to crawl through the crack in the wall between the guards. Or it simply embodies the culture of Rust at the time - one of a massive group of people getting their hands dirty and getting shit done.<p>The fourth truly made me smile. Yes, its lesson about macros was correct - at least then. I doubt they have gotten much easier to use. However, they are useful to work with to get a feel for manipulating the raw syntax of the language. Writing some toys with them is sure to teach you a thing or two about using the language without them.