That acm article was very interesting, than you! Lots of nice little concrete examples - that are simple, yet not too simple.

I've yet to play much with ocaml — we had a bit of standard ml in our programming paradigms-class at university (at the time the course used [1] "Programming Languages: Concepts and Constructs (2nd Edition) by Ravi Sethi" — now they've (unfortunately, yet understandably) replaced standard ml with Haskell). I've since had a little trouble adapting to similar-yet-different languages like both Haskell and OCaml.

[1] http://www.amazon.com/Programming-Languages-Concepts-Constru...