(to-array-2d coll)
Returns a (potentially-ragged) 2-dimensional array of Objects containing the contents of coll, which can be any Collection of any Collection.
user> (def a (to-array-2d [[1 2 3][4 5 6]]))
#'user/a
user> (alength a)
2
user> (alength (aget a 0))
3
user> (aget a 0 0)
1
user> (aget a 0 1)
2
user> (aget a 0 2)
3
user> (aget a 1 0)
4
user> (aget a 2 0)
→ ERROR
nil
user>
;; quick example of a ragged array where the length of each element of the
;; 2d array is unique
user=> (def a (to-array-2d [[0][1 2][3 4 5][6 7 8 9]]))
#'user/a
user=> (map alength [(aget a 0)(aget a 1)(aget a 2)])
(1 2 3)
user=>
user=> (aget a 0 2)
ArrayIndexOutOfBoundsException java.lang.reflect.Array.get (Array.java:-2)