I've gotten the code I wrote for my Haskell Love talk into (just barely) good enough shape to make an initial release. So far, I have implemented stacks and queues that take n + O(log n) space, and whose basic operations take O(log n) time. I hope to add deques soon. More urgently, I need to write a test suite. Furthermore, I have written only "simple" versions, that directly use the mechanism described in my talk. To get decent performance, it will probably be necessary to add a layer on top of that. The package can be found at http://hackage.haskell.org/package/compact-sequences-0.1.0.0 David Feuer