Functional Approach to java

I was wondering if this book already covers certain new possibilities for FP using the functionality currently in preview mode.

Hi Simon!

The book's upper ceiling is Java 17, as it was the current LTS version at the time of writing.
If there's something on the horizon, I mention it, link to JEPs, might even tease a little code, etc., but don't go into much detail.

My reasoning was that many Java devs are still stuck on 11 or even 8.
If they finally get to use a new version, I think it's unlikely they will switch directly to 21 with preview features enabled.
And, to be honest, the book was initially planned to be no longer than 275 pages.
I ended up with a 403 pages book which took quite some more time to write...

So where do you begin to cut or draw the line?
I concentrated on available features instead of upcoming ones, as preview features might still change, and printed books are kind of immutable data structures that can only be fixed with new editions

That's indeed always the question, and thank you for the swift reply.
Linking to things on the horizon/teasers indeed sounds like a good approach.