(= cube-list (map [expt _ 3] (range 1 10)))
(= acc 0.000000000001)

(def search-real (cr of rn)
  (let gosa (- rn (expt cr 3))
    (if (< (abs gosa) acc)
        cr
        (if (< 0 gosa)
            (search-real (+ cr of) (/ of 2) rn)
            (search-real (- cr of) (/ of 2) rn)))))

(def search-cube-root (rn)
  (if (is (type rn) 'int)
      (let i (trunc rn)
        (if (mem i cube-list)
            (+ (pos i cube-list) 1)
            (search-real (+ (pos i (sort < (cons i cube-list))) 0.5) 0.25 rn)))
      (search-real (+ (pos rn (sort < (cons rn cube-list))) 0.5) 0.25 rn)))