Re:A database backend would go a long ways... (Score 1)

In Common Lisp, the first form in the body of a function is the documentation string. (And since strings evaluate to themselves, it's ignored, unless it's the only form)

(defun foo_up (x y)
"This completely foos up x and y."
(+ (* x y) (/y x) (sqrt (- 2 x))))

Since code is represented as data (a tree) in lisp, it's easy to parse the doc string out of the function definition.

You just need a versioning system that knows S-expressions.