No, the book will only go into implementing single dispatch. I'd love to talk about implementing multimethods, but I don't know how to implement them very well either. :) I've read a few papers on it, but there doesn't seem to be a lot of literature. Maybe it's mostly locked up in tribal knowledge and you have to be in the right room with the right people to learn it.
This is sad.
OT: With Google Chrome's new Turbofan, and its altered inlining budgeting, there now seems a chance of inlining dispatch trees. Combined with PICs, and cpu branch prediction and speculation... there seems hope for wizzy multiple dispatch in javascript. Maybe. I don't know of anyone pushing on it.
Kotlin goes this direction, for example, though it still requires an annotation on all functions that participate in continuations. This makes it fairly straightforward to tell where the `prompt` is- the root `suspend fun` passed to whatever API drives it. Making every function implicitly `suspend` would let you treat any function as a `prompt`.
---
Other pet peeve of mine is how build control-flows. Using continuations is complicated (I'm using F#) and cause a drop in performance. I wonder what else could be use that allow to make exceptions/coroutines.
Or how make delimited continuations to work reasonable well. The code I have found is in scheme/lisp and it look hard to dechiper.