gistfile1.clj

(require '(criterium [core :as q]))

(def ranges [-1 2 5 10 20 40 80 500 1500 Long/MAX_VALUE])

(defn create-partitioner 
  "returns a function that accepts a number, and returns i if the number is between h(igh) and l(ow)
   otherwise returns nil"
  [l h i] (fn [v] (if (and (<= v h) (> v l)) i nil) ))

(defn part 
  "returns a function that gets a value and returns the group which the value belongs to"
  [r] (let [s (map (fn [l h i] (create-partitioner l h i)) ranges (rest ranges) (range))]
        (fn [v] (some #(% v) s))))

(def p (part ranges))

(q/bench (dotimes [n 10000] (p (rand-int 1600))) :verbose) ;;; my version


(def range-groups
  (into [] (map vector ranges (rest ranges))))

(defn get_group [freq]
  (first
    (filter
      (fn[[low high]]
        (and (> freq low) (<= freq high)))
      range-groups)))

(q/bench (dotimes [n 10000] (get_group (rand-int 1600))) :verbose) ;;; your version