Advice needed: separate out chapters on object models?

[Brian Marick]

TL;DR: Should I split the book in two, moving all the optional material on object models into another a second book? Poll here: http://www.surveymonkey.com/s/YLXKK78

By way of background: I've moved chapter 7 (The Class as an Object) into the optional Part V (Variations on Object Models). That's in keeping with thinking of Part 1 as an extended introduction to Clojure and functional programming that uses an interesting running example much more than it being about object models per se. It builds an example that justifies introducing ideas like functions-as-objects and recursion, then drops you into Part 2, which is explicitly about functional style.

At the same time, the optional chapter on prototype-based languages has expanded into two chapters. One on how such languages differ from class-based languages, and another that implements the Javascript object model by implementing it in Clojure. (Given that Javascript's object model is widely used, somewhat idiosyncratic, and easily misunderstood, I thought that might be a service.)

However, that leaves me with somewhere around 100 pages devoted to optional material about object models. I worry about that for two reasons:

* It makes the book look much longer than its essential core (which is 220 pages), and people shy away from long books (even if they notice that 125 pages [including the optional monad text] are marked as optional).

* People who are interested in object models but not functional programming will never find the material.

So I'm toying with the idea of splitting the optional chapters on object models out into a separate book. It would share everything up through the end of Part 1 with the current book.

Disadvantages of that:

* People who've bought the current book will feel I've taken something away from them. That's true even if I (as I would) give current purchasers a coupon for a free copy of the new book. It's still inconvenient.

* How many people who are interested in object models are willing to learn Clojure to read a book about them? (Maybe I should write it in Javascript?)

* Sharing text and exercises between two books will be a hassle, even though it's supposed to be one single big chunk.

I welcome your opinion, whether as a vote on the poll or a note here.

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Brian Marick, Artisanal Labrador
Contract programming in Ruby and Clojure
Occasional consulting on Agile
Writing /Functional Programming for the Object-Oriented Programmer/: https://leanpub.com/fp-oo