Validating credit card numbers in Clojure

	(ns valid-credid-card)
	(defn- parse-int [s]
	(Integer. (re-find #"\d+" (str s))))
	(defn- to-digits [n]
	(map parse-int (str n)))
	(def ^:private to-digits-rev
	(comp reverse
	(partial to-digits)))
	(defn- double-second [coll]
	(map-indexed
	#(if (zero? (mod (+ %1 1) 2))
	(* 2 %2)
	%2)
	coll))
	(def ^:private sum-digits
	(partial reduce #(+ %1 (reduce + (to-digits %2)))))
	(defn is-valid? [num-credit-card]
	(zero?
	(mod
	(->>
	num-credit-card
	to-digits-rev
	double-second
	sum-digits)
	10)))

view raw valid-credit-card.clj hosted with ❤ by GitHub