generating strings of radix numbers for clojure

gen_radix_numbers_as_strings.clj

(require '[clojure.string :as cs])
(require '[clojure.test.check.generators :as gen])

(take 20 (gen/sample-seq
          (gen/let [sign (gen/elements ["" "+" "-"])
                    radix (gen/choose 2 36)
                    r-or-R (gen/elements ["R" "r"])
                    n gen/nat
                    nums (gen/vector (gen/choose 0 (dec radix))
                                     (inc n))
                    caps (gen/vector gen/boolean
                                     (inc n))]
            (str sign
                 radix
                 r-or-R
                 (cs/join (map (fn [num cap]
                                 (if (<= num 9)
                                   (char (+ num 48))
                                   (char (+ num (if cap 55 87)))))
                               nums
                               caps))))))