(defun f (x)
  (match x
         ( (apa (? x) (? y)) (> x y) 'bigger)
         ( (apa (? x) (? y)) (< x y) 'smaller)))



(check (and (eq (f '(apa 0 1)) 'smaller)
            (eq (f '(apa 1 0)) 'bigger)
            (eq (f '(apa 1000 900)) 'bigger)
            (eq (f '(apa 900 1000)) 'smaller)))