Emacs Lisp's Future(lists.gnu.org)

  ;; valid elisp and cl, same result in each
  (defun foo (bar) (+ 1 bar))
  (defvar foo 4)
  (foo foo) ;; makes perfect sense in CL and elisp,
            ;; but none in scheme

  ;; syntactically valid scheme, won't work on the last line
  ;; which translates to (4 4) and so makes no semantic
  ;; sense.
  (define foo (bar) (+ 1 bar))
  (define foo 4)
  (foo foo) ;; will break in scheme because foo is now 4
            ;; and 4 can't be applied as a function