I dunno, I wouldn't say this is as readable as the author mentions. To me, all of the chaining, syntax for closures, and Rust concepts like "into_iter" work to hide the actual algorithm, which is pretty simple. And forget testing, since this is all actually ONE top level call. I certainly wouldn't want to maintain code written like this in any language (and yeah, while you could make pretty much the above in C++ if you really wanted, I wouldn't write it that way.)