Excellent idea. I think maybe having strict type interfaces for the implementation so you could roll your own would be a good idea too; à la perl's tie HASH =>

Excellent idea. I think maybe having strict type interfaces for the implementation so you could roll your own would be a good idea too; à la perl's tie HASH => TIEHASH, FETCH, STORE, et alia, TIEARRAY, FETCHSIZE, STORESIZE, et alia, etc. Obviously then you can have slices, arrays, maps (hashes, dicts), that can be use whatever backing store / behaviour you want / need. This will mean that behaviour of individual data collections may not be as clear cut in their behaviour (skeuomorphically) but the upside is more flexibility.