The "About this book" tells you what the book covers. The whole book is available for you to peek at if you don't trust it to correctly summarize itself. As yo

The "About this book" tells you what the book covers. The whole book is available for you to peek at if you don't trust it to correctly summarize itself. As you would expect, Rust does have concurrency primitives, which is why the book shows you how they are implemented and why they are implemented they way they are. In doing so it also teaches you how to do low level things for when you can't use the language provided primitives, like if you're interacting with FFI boundaries or implementing your own lockless datastructure. Your comment is like seeing a link to "Learning Rust With Entirely Too Many Linked Lists" and reacting with "what language doesn't have linked lists?" Edit: I see that you might have meant "why would I reimplement Rust's atomic primitives in another language". Well, some documentation is needed for anyone that will have to implement those language primitives, in existing languages (because there are undressed needs) or in new ones. More documentation and explanation of tricky concepts is good.