=LET(
ARRAY, LAMBDA(dim, [init], LET(
Y, LAMBDA(SELF, arr,
LAMBDA([a], [b],
IF(ISOMITTED(b),
INDEX(arr, a),
SELF(SELF, IF(SEQUENCE(ROWS(arr)) = a, b, arr))
)
),
Y(Y, IF(SEQUENCE(dim), IF(ISOMITTED(init), "", init)))
)),
my_arr, ARRAY(5, 0),
...