Defining a "minimum" function to return the minimum of a list using another function that returns the smaller of two numbers

Question

(defun *smaller* (x y)
  ( if (> x y) y
        x))
(defun *minimum* (lst)
  (do ((numbers lst (cdr numbers))
       (result (car numbers) (*smaller* result (car numbers))))
      ((null numbers) result)))

LISP says that variable "numbers" in "minimum" function is an unbound one although I think I've bound it to "lst". What am I missing?

Answer 1

Do binds in parallel. The expression for the initial value of result is (cdr numbers), and numbers is unbound there. Do* would work here.