Emacs Lisp Function Guide?

Have you tried the build-in manual in emacs? Open any lisp buffer (or any buffer in lisp mode), move your point to any function or variable, and hit C-h f (for function) or C-h v (for variable). Emacs will give you a fairly concise description of the function/variable.

For example, the manual content for (save-excursion) is

save-excursion is a special form in `C source code'.
(save-excursion &rest BODY)

Save point, mark, and current buffer; execute BODY; restore those things.
Executes BODY just like `progn'.
The values of point, mark and the current buffer are restored
even in case of abnormal exit (throw or error).
The state of activation of the mark is also restored.

This construct does not save `deactivate-mark', and therefore
functions that change the buffer will still cause deactivation
of the mark at the end of the command.  To prevent that, bind
`deactivate-mark' with `let'.

The good thing also is the build-in manual give you "link" to to the source code of the function and to other functions that might be related, which make it nice to browse around.

Of course you can't learn lisp this way, but for looking up documentation of function this is a nice starter. When you find the build-in manual not understandable (which sometimes does happen), then it's time for you to google the function ;)

The GNU Introduction to emacs lisp is certainly more approachable than the reference manual.

I would add a couple of things:

• M-x apropos - searches functions and variables for whatever string you specify (e.g. directory). Note that this is slightly different than C-h a, which only finds interactive functions

• find a similar piece of code and copy it - you can learn an awful lot about how to do things by looking at what's already done. If you have a particular function you want to see examples of, one good way is to visit the main lisp source directory in dired (e.g. d:/product/emacs/lisp or /usr/share/lib/emacs/lisp) and do % g which will grep through all files looking for whatever string you type. Open up that file and see what other people have done with it.

• C-h f and C-h v - as someone else mentioned, you can open up source, position point over a function or variable and then get documentation on it.

• Check out the Emacs wiki, which has a crap-load of Emacs lisp modules for you to peruse.

This site has some emacs lisp summary information that may be useful: http://xahlee.org/emacs/elisp.html.

In particularly, check out these links on that page: Basic Text-editing Functions, Emacs Lisp Idioms and Batch Text Processing