How to generate repeatable random sequences with rand-int

Question

I want to be able to generate repeatable numbers using rand in Clojure. (Specifically, I want results of calls to rand-nth or Incanter\'s sample

Answer 1

Probably not the cleanest way, but you can make it work by redefining clojure.core/rand:

(ns clojure.core)

(def r (java.util.Random. 1))

(defn rand
  ([] (.nextDouble r))
  ([n] (.nextInt r n)))

(take 10 (repeatedly #(rand-int 10)))

This produces (5 8 7 3 4 4 4 6 8 8) every time I run it.