Just something similar to the hashtable implementation would be enough:

acopy <array1> <array2>
; Copy an array to another.

amake <array> <size>
; Create an array.

aadd [-imo] <array> [N] <data>
Add data to an array.
-i = insert <data> at position [N]
-m = make array if it doesn't already exist.
-o = overwrite item at position [N] with <data>

adel <array> <N>
; Delete an item from an array.

aunset <array>
; Delete an array.

; Get data from an array.

Find data within an array.
r = regex comparison
w = wildcard comparison

The main advantage over hashtables would be that they could be used to store sorted data, without having to use slow file access. As per usual, using 0 for the <N> parameters for the identifiers will return the number of found matches / total number of items.