Thought I'd mention http://hackage.haskell.org/trac/ghc/ticket/2143 as being in libraries@ bailiwick. It's been a while since http://neilmitchell.blogspot.com/2008/03/sorting-at-speed.html and http://haskell.org/pipermail/haskell-cafe/2008-March/thread.html#40164 but I hope with some Criterion benchmarks, the case for replacing the current GHC Data.List.sort with the YHC Data.List.sort becomes a no-brainer. (If people want to improve the Criterion benchmark and run it themselves to verify that YHC is always faster, that'd be great also!) -- gwern