Hello, I've been playing about with a bit of applied AVLism to implement (hopefully) efficient String maps. I've posted what I've done so far here.. http://homepages.nildram.co.uk/~ahey/HLibs/Data.StringMap/ It's early days so it's a bit limited and hardly tested at all. I just want to ask peoples opinions on this before I go further. Like.. Does anybody object to me usurping the Data.StringMap slot in the hierarchical namespace? It seems to be vacant at the moment but maybe someone has other ideas about how this should be filled. Is anybody working on possible alternatives? If so it would be good to do some performance comparisons. I think the data structure I've used will turn out quite efficient, but there are other possibilities like using packed strings and/or hashing. Any suggestions or feature requests? Also, I'd be grateful someone could tell me what the data structure I've used is actually called :-) Thankyou -- Adrian Hey