I'll echo GeoffKnauth, I'm glad to have paid you for several of your books. I'm looking forward to starting the introduction to Klong book, as I find array languages fascinating but there's a regrettable lack of beginner materials for many.

Incidentally, the 6x9 PDF size is great on a Kindle Oasis, the print is a bit small but it works. This is in contrast to most other PDF ebooks, which I would have great difficulty reading on the Kindle, so thank you also for that!