A Function Table Is an AssociativeArray that has a key of type symbol and a value of type function. in scheme you can do this
  (define (foo x y)
	((assq x <foo>) y))
  (define <foo> (list (cons 'foo (lambda (x) (+ x x)))
			(cons 'bar (lambda (y) (* y y)))))
Function tables can be used like Extensible Case Statements  where the key is the case and the function is the code.