[wrycoder]

Nand2Tetris is also like that - they provide an outline and tests, but you have to do the work. And, having the implementation language be different from the target language reduces confusion.

Plus, you get to become proficient in OCaml, which is a pretty good language.

[kragen]

that's a good point—it was pretty confusing when i wrote ur-scheme in scheme, or stoneknifeforth in stoneknifeforth, because i kept getting confused about which level of the language i was changing things in