Doubling all the numbers

gistfile1.clj

;; I have a sequence and I want to double all the numbers up to a limit. The following works, but looks awful!

;; (defn double-all [numbers limit]
;;  (for [val numbers :when (< (* 2 val) limit) ]  (* 2 val)))

(defn double-all [numbers limit]
  (filter #(> limit %) (map #(* 2 %) numbers)))

(double-all (range 20) 10)

1 - I think there's a better construct than the (for);
2 - The (* 2 val) is repeated

Much better now i guess!

(defn maybe-double [n, max](let [double %28* 2 n%29] %28cond %28< double max%29 double :else n %29))
perhaps?

(clojure noob here as well ;)

best I can come up with to use it is (map maybe-double [1 2 3 4 5] [10 10 10 10 10]) which isn't very elegant :p

(map #(maybe-double %1 10) [1 2 3 4 5])

Hmm thanks! I'm thinking. I'm using this to implement the Sieve of Erasthotenes... let me check what I can come up with.