to-array

user=> (to-array [1 2 3])
#<Object[] [Ljava.lang.Object;@b2bb14>

(def hello (to-array "Hello World!"))

(aget hello 1)
;; => \e

(aset hello 1 \b) ;;Mutability! Watch out!
;; => \b

(dotimes [n (alength hello)] (print (aget hello n)))
;; => Hbllo World!

;; Calling `to-array` on array returns the original, not a copy
(identical? (to-array hello) hello)
;; => true

user> (class '(1 2 3 4))
;=> clojure.lang.PersistentList

user> (class (to-array '(1 2 3 4)))
;=> [Ljava.lang.Object;

user> (get (to-array '(1 2 3 4)) 0)
;=> 1