Rest assured that I haven't given up on the textbook / tutorial approach just yet, but I might have to "invent" my own publication technology to get the "book" that I want.
Would it be hard to just create a Dyalog-APL notebook (I recall Dyalog added support for that recently) and export as PDF?
I find Jupyter notebooks in Python and Wolfram's Mathematica to be nearly perfect for explaining complicated content where you can easily format text, images, and inline code snippets.
