Add a section on lambda's.

Dissuade their use when named function is better.
Prohibit quoting.
Move existant lambda information into section.

This will conflict with #12 . I'll rebase locally if #12 is merged here.
Indeed.

On Friday, September 5, 2014, Artur Malabarba <notifications@github.com>
wrote:

> In README.md:
>
> > @@ -338,6 +329,49 @@ name clashes.
> >
> >  * Prefer syntax-quoted forms over building lists manually.
> >
> > +## Anonymous (lambda) functions
> > +
> > +* Use `lambda`s for local bindings and function calls, **not** for
> > +  hooks or global variables. Define named functions for the latter,
> > +  they aid readability and customizability.
> > +
> > +    ```el
> > +    ;;; Good
> > +    (mapcar (lambda (x) (or (car x) "")) some-list)
> > +    (let ((predicate (lambda (x) (and (numberp x) (evenp x)))))
> > +      (funcall predicate 1000))
> > +
> > +    ;;; Bad - Define real functions for these.
> > +    (defcustom my-predicate (lambda (x) (and (numberp x) (evenp x)))
>
> You're right, maintainability isn't an issue in that case, but readability
> still is. And in the case of defcustom, you're exposing a rough lambda to a
> large range of less-savvy users, where you could be exposing a reasonable
> name of a well documented function.
>
> But I agree it's important to be reasonable. We could recommend a named
> function, instead of saying it's wrong.
>
> —
> Reply to this email directly or view it on GitHub
> <https://github.com/bbatsov/emacs-lisp-style-guide/pull/18/files#r17188594>
> .
>


-- 
Best Regards,
Bozhidar Batsov

http://www.batsov.com