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

From what I understand, none of the above are functional approaches. If you want that, you can use a lazy-seq:

(letfn [(f [randomizer]  (lazy-seq (cons (.nextInt randomizer) (f randomizer))))]
  (defn create-random 
    ([] (f (java.util.Random.)))
    ([seed] (f (java.util.Random. seed)))))

To get the first random number you use:

(first (create-random 0)) ;; using 0 as seed

To get the rest of the sequence you use:

(rest (create-random 0)) ;; again 0 as seed

To get the first element and a reference to the rest you can use:

(defn pop [x (create-random 0)]
     (n, rest) `(~(first x) ~(rest x)))