overflow - 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 * (range 1 1001)).

Answer 1

You could use the *' operator which supports arbitrary precision by automatically promoting the result to BigInt in case it would overflow:

(reduce *' (range 1 1001))