;;;; into over elements that own storage. Without a (map f) in the chain the
;;;; elements are pushed as they stand, which copies their headers and shares
;;;; their blocks — so that is refused, and (map clone) is the copy that
;;;; compiles. The outer Vecs are in an arena, as a container of owning
;;;; elements has to be; the inner ones are on the heap, where growing one
;;;; through a shared header would free the block the other still points at.

(defn main [] i32
  (let [a (arena-new 65536)
        v (vec-new (Vec i32) a)]
    (push v (vec-new i32))
    (push (at v 0) 1)
    (let [w (into v (vec-new (Vec i32) a) (map clone))]
      (dotimes [i 100] (push (at w 0) i))
      (println (at (at v 0) 0))                  ; 1
      (println (length (at v 0)))                ; 1
      (println (length (at w 0)))                ; 101
      (println (at (at w 0) 100))                ; 99
      (free (at w 0)))
    (free (at v 0))
    (arena-destroy a)
    0))