For what it's worth, I'm the one who suggested to Gwern that he update the cabal stuff for collections. Someone had remarked that there was no good way to make use of various collection types in the standard libraries, and I knew that the collections package on hackage took steps toward rectifying that. But, it didn't build on 6.8, due to what looked like a split-base issue. I knew Gwern had experience fixing up cabal-related stuff, so I told him he might want to try getting them fixed.
FWIW (again) : * I think collections-api is a good base to give a uniform API to a lot of data structures on hackage. - It uses FD style though, so one might want to adapt it to AT soon. (I tried with GHC 6.8 but support was too buggy). - In particular, it can be useful to write a polymorphic testing and benchmarking framework. * I have no time to maintain collections. As Adrian said before, this is an unpaid, thankless job, so my motivation went downhill since I started the project. * I did not remember that Adrian had reclaimed some parts and uploaded them separately. Corresponding code in the collections repo should be removed and the rest adapted to use Adrian's version. * Hence, I gave a "don't care" signal to Gwern when he proposed uploading to hackage. We already discussed this before, but that repository can be considered orphaned. I'll give pointers to anybody interested in adopting it. Cheers, JP.