The one possible change would be to allow "in" with statically-sized arrays, under the assumption that the amount of data searched is fixed and proportional to the size of the program.
To be really consistent,
x in arr
would need to be equivalent to:
(x >= 0) && (x < arr.length)`in` tests for the presence of a _key_ in AAs, and the equivalent notion of a key for arrays is an index.
