I don't find it that surprising. It's the Literate Programming Knuth came up with ages ago. I own a book called 'Physically Based Rendering' which deals with rendering images through, essentially, simulation of the physics of light which is written in the same manner. As far as I know, Knuths work and the Physically Based Rendering book are the only ones published which are of that type... well until I saw this posting this morning, that is!