Thanks for reporting. I know that some books use a lot of diagrams for the explanation, e.g. the one from the Brown University, and the book of Jim Blandy. I still wonder if such diagrams are needed and helpful. For me personally, I doubt it. I recently revised chapter 6, "Ownership and memory management" of my book, and have the feeling that a good text is all we need. But in the next weeks I will try to study this thread, and try to understand which problems people have and if I have again to adapt chapter 6. At least for me -- I studied all the diagrams in the book of Jim Blandy and saw no benefit, more just a waste of space in the book and waste of time for the reader. For the book from Brown University some people had a similar experience. A diagram can not really compensate a bad textual explanation, and a good textual explanation needs no diagrams. Maybe for young children it is different.
I absolutely agree with your point that a diagram cannot compensate poorly written text. I do believe it can help though â if only to give the reader a pause to breathe and reflect (with some visual help) on what they read. It is of course debatable whether rustviz is the correct tool in this thread since it requires quite some setup to use.
Text is the most flexible communication technology. Pictures may be worth a thousand words, when there's a picture to match what you're trying to say. But let's hit the random button on wikipedia and pick a sentence, see if you can draw a picture to convey it, mm? Here:
"Human rights are moral principles or norms that describe certain standards of human behaviour, and are regularly protected as legal rights in national and international law."
Not a chance.
That said, I think the diagrams in chapters 4 and 5 of Programming Rust are the second-most-praised feature of the book. (The first is chapter 2.) People like them. I've even run across someone copying pictures out of the book and pasting them into Stack Overflow to explain somethingâplagiarism, the sincerest form of flatteryâand here's someone asking how they can generate such diagrams for their own data.
That alone does not prove they are valuable; people like and praise all kinds of silly stuff. But I think there is a good psychological reason to include figures, similar to the role of sample code and exercises. The same information is presented in a different way. It's an opportunity for the reader to check whether they understand, to use their brain actively (is this what the text said?), and to recover from minor misunderstandings.
For me, good exercises are better. Not everybody likes homework though.