A problem in the SRFI has been brought to my attention, namely that hash-by-identity is not required to remain the same for mutable structures if you change their contents (and indeed won't in the reference implementation). Arguably this guarantee should be made, as lack of it seriously lowers the value of eq? hash tables.
However, there is this problem that there is no way to portably provide an appropriate hash function that will provide change consistency. The best one can do is to give a dummy function that returns the same hash value for e.g. all pairs (thus making hash table lookup an O(n) operation) or to give a assq-cache backed hashing function (thus making hashing on O(n) operation). Both will fail the appropriateness requirement of the SRFI. So there's no way to implement the SRFI portably, if change consistency is added. Any ideas / suggestions on how to best approach this? Panu -- personal contact: [EMAIL PROTECTED], +35841 5323835 technical contact: [EMAIL PROTECTED], http://www.iki.fi/atehwa/ PGP fingerprint: 0EA5 9D33 6590 FFD4 921C 5A5F BE85 08F1 3169 70EC
