How to use elisp's closure

[netawater <netstandin-003@yahoo.com.cn>]

In most usual modes, TAB key is bound to an indent function and
M-TAB key is bound to a complete symbol function. 
I want to write a function if cursor is at the end of word then 
try to complete symbol, else indent. It is my function.

(defun my-indent-or-complete (M-TAB-func TAB-func)
;;   "If cursor is at the end of word then current mode;s M-TAB 
function, else TAB"
  (lambda ()
    (interactive)
   (if (looking-at "\\>")
       (apply M-TAB-func '())
       (apply TAB-func '())
     ))
  )

Then I try to bound it to \t key:

(add-hook 
 'find-file-hook 
 '(lambda ()
    (let ((M-TAB-func (key-binding "\M-\t"))
	  (TAB-func (key-binding "\t"))
	  )
     (local-set-key 
      "\t" 
      (my-indent-or-complete M-TAB-func TAB-func)))
    )
 )

However it does not work, it says Symbol's value as variable 
is void: TAB-func. I think it is because my function is not
a closure, but how can I resolve it?

Thank you very much!