> I'm not sure if you are asking about Python, or Ruby. Ruby, since you said it allows mutable keys in dictionaries. > Anyway, both languages use value-based

> I'm not sure if you are asking about Python, or Ruby. Ruby, since you said it allows mutable keys in dictionaries. > Anyway, both languages use value-based hashing for dictionaries. Neither Python nor Ruby has compound values. Object identities are primitive values. > but I guess you are just expected to not mutate the keys? I guess C programmers are expected not to use memory after they free it.