CL-USER> (loop for number in '(1 2 3 4 5 6 0 7 8 9)
               for i from 0
               for minimum-index = (cond ((null minimum-index) 0)
                                         ((< number minimum) i)
                                         (t minimum-index))
               for minimum = (if minimum (min number minimum) number)
               finally (return minimum-index))
6
CL-USER>