[DanWaterworth]

I'd expect either Rank2Types or RankNTypes to be included in Haskell', you may be thinking of ImpredicativeTypes.

Wow, I did not realize ScopedTypeVariables had been around for so long.

[taylorfausak]

Sorry, I meant that you pretty much always want RankNTypes instead of Rank2Types. My fault for not specifying.