ClojureScript Factory Pattern Example

bignum.cljs

(definterface IBigInt
  (add this y)
  (subtract this y)
  (multiply this y)
  (divide this y))

(defprotocol BigInt [signum magnitude]
  IBigInt
  (add (add this y))
  (subtract (sub this y))
  (multiply (mul this y))
  (divide (div this y)))

(defn big-int [num]
  (if (= (typeof num) "String")
    (BigInt (sig-from-str num) (mag-from-str num))
    (BigInt (sig-from-num num) (mag-from-num num)f)))