I noticed that the Down newtype (whose Ord instance inverts its payload's ordering) currently only exists in GHC.Exts, and it seems like something fairly generally useful. What do people think of moving it to (or re-exporting it from) Data.Ord? Moving it would be nicer, but the fancy list comprehension desugaring might want it in GHC.Exts, so I'm not sure what the consequences would be.