[Haskell-cafe] Can cabal detect property of the platform ?

Hi Cafe, Is there a way to have (some) cabal flags to autoconfigure themselves ? For example, a SSE flag, i want the configure to default to on when the building machine has SSE instruction available, and default to off otherwise. (of course, it wouldn't affect the user ability to override the default with -f) It doesn't appears possible just using the cabal file. Is there a way with the Setup.hs maybe ? or some other cunning plan ? -- Vincent