I'm interested in learning expl3 because allows flexibility in macro writing and, unlike Lua, it is supported by most TeX engines. I've read the following questions and answers with respect to expl3 documentation when searching for examples of code, not as helpful as I expected:
Forthcoming LaTeX3 User Manual (there's no actual user manual)
The questions have 3 o 4 years posted and the documentation so far is a bit sparse, I think. So, I want to know if there are manuals or similar documents more "example-based" of expl3 or written at a slower pace.
expl3.pdfis a (gentle) introduction, then you can dive ininterface3.pdf. “Little examples” are in great number on this site and there are also examples ininterface3.pdf. I believe you would get better help if you asked a specific question concerning a specific point you don't understand. :-) (all this assumes you have a small background in TeX programming, e.g. having read and understood a good part of the TeXbook, and practiced a bit writing of TeX macros, because theexpl3docs assume you understand important TeX concepts: tokens, expansion, macros, boxes, modes...) – frougon Apr 22 '20 at 08:00