Disclaimer: I got this book as part of the bloggers review program at O’Reilly.
You will learn about how to work with Opa “the framework” and about some of the language features.
The book achieves this with several hands on projects of varies and increasing complexity.
There are only a few chapters that are not practical, ex: explaining the opa type system (chapter 7) and a few short introductory chapters at the beginning of the book. Read those chapters because they are packed with good information on some of Opa’s strong points
The book is targeted to developers of an intermediate level, without leaving in the dark beginners.
The authors don’t waste to much time describing concepts outside Opa itself, a beginner may have to do some reading on the side to supplement knowledge, but it should be able to get to work with the framework regardless.
I think it’s a good compromise since keep the book focused on the task and keep it short.
There are no tests at all in the book nor mention of unit test, assertions or testing libraries/modules. For me this is not a good thing. A book written today should (at least), describe how to test your system. Even if it’s in an appendix of the book, so to keep the examples clean.
Opa is an intriguing framework and I will have to take it for a spin to make my mind about it. The book convinced me that I should at least spend some time with it.
There are a few other things that bother me, but those are regarding the code examples and the framework and may not be really the book to blame (ex: not external templates, to separate html from the view code).
I also recommend taking a look at some of Adam Koprowski’s repos on Github