No one seems to support Edison. However, there is an important difference between Edison and DData: DData provides implementations of specific structures, while Edison tried to provide general collection interfaces *and* implementations. I believe that designing good generic collection interfaces is very hard and may even be impossible to do "right" in current Haskell's. So, I guess we will be stuck with concrete data structures for a while :-)

I second Daan's opinion here. The Haskell community has been searching for good generic collection interfaces for a while and hasn't come up with anything that is obviously the right thing. In the meantime we're stuck with poor data structure support because everyone is waiting for the wonderful generic collection library to come along. Having a well-designed and consistent concrete data structure library is certainly a lot better than nothing. Indeed, it would be more useful in a sense because the barrier to adoption would be low, and it wouldn't have an impact on the existing libraries. If such a thing were to materialise, I'm sure we'd import it into the hierarchical libraries that are shipped with GHC, Hugs & nhc98. Perhaps DData is pretty close to what we're after. Would the interested parties care to thrash out the details and present it to the wider community for comments? Cheers, Simon