The linked document isn't representative of books on Lisp or Emacs---it reads like a half-finished idea for a sketch of a pitch for a book. Since it is more than 10 years old, the project likely got abandoned at a very early stage. Writing a book is a lot of work, so don't mean this as criticism against the author. Just thought I'd say it in case someone doesn't want to waste time downloading and building something unfinished.
The easy way is thru the late Robert Chassell's book "Emacs Lisp Intro". I know someone mentioned it , but I bought a hard copy of Chassell's book and its great to learn, esp from one of the core members, in a different style. My brain refuses to dig books written in the same "new" way.
The right way IMO is to just start customising your Emacs with a very ready and very introspectable distribution (like Doom or Spacemacs) and then poke around to fix what you don’t like.<p>Though I guess a book can be helpful to learn best practices. But with how excellent the emacs documentation (including describe-function, describe-variable and describe-key, to know what you should edit) you can just jump in right away.
The link to <a href="http://learn-elisp-for-emacs.org/" rel="nofollow">http://learn-elisp-for-emacs.org/</a> seems to be broken, redirecting to <a href="https://www.gooroo.com/" rel="nofollow">https://www.gooroo.com/</a> instead...
Another option is to look at existing modules on MELPA, standing on the shoulders of the giants etc.<p>I really learned a lot from org-roam-ui [0]:<p>- websockets
- http server
- creating an API
- and of course internal emacs functionality.<p>[0]: <a href="https://github.com/org-roam/org-roam-ui" rel="nofollow">https://github.com/org-roam/org-roam-ui</a>