What's Rattlesnake? I can't find anything at all online.

I think he's referring to Python, just like other made up names probably refer to Java, Js, C++ and OCaml.

Ahh I see, I didn't notice that name in the article, thank you.

+1

Wanted to say the same. He straight up conjured a good looking code in CrabML as an example of similar level of "ugliness", while it has about three times less syntax noise.

It ends in ";;". If that's not a typo, and it's semantically significant that there are two semicolons instead of one, that sounds quite finicky.

     The answer to the question “When do I need the ;; within OCaml source code?” is never.

     It's not a part of the language and is only used by the interpreter as an end of input mark. 

     Historical note: In CAML Light, the predecessor of OCaml, double semicolons were mandatory. For this reason they are quite common in old code originally written in CAML Light or written in the early days of OCaml. These days they are considered a bad style. 

from https://baturin.org/docs/ocaml-faq/#the-double-semicolon

Choked on my coffee when I got to Rattlesnake. Great name.