Clojure - Calculate with big numbers

Question

I want to calculate !1000 in clojure, how can I do this without getting a integer-overflow exception?

My factorial code is right now: (reduce * (r

Answer 1

Coerce the parameters to clojure.lang.BigInt

(reduce * (range (bigint 1) (bigint 1001)))

I.e. if you are working with an third-party library that doesn't use *'

(defn factorial' [n]
   (factorial (bigint n)))