Second method of embedding functional code in OO should not be so easy to miss

[jeremy-w]

My first read-through of Chapter 8, "Embedding Functional Code in an OO Codebase", garrulous gastropod, I finished reading the chapter with the impression that the introduction mentioned 2 approaches and the chapter only described 1.

Closer reading revealed that approach 2 ("OO coating around a gooey functional center") is mentioned almost as an aside in the conclusion of the chapter.

It would be interesting to see this given the same weight as the first approach ("chunky functionalism"), as well as some text putting these approaches in the context of the leading practices of object-functional languages like F#, OCaml, and (of course) Clojure. What do people end up doing when mixing OO and FP is nearly frictionless?

Is there any extant code in non-object-functional, but rather object-oriented, languages that you'd recommend reading as a good demonstration of this style?