[Haskell-cafe] translating from fundeps into type families

Hi, Can I have some advice on translating the attached Test1.hs into type families? My attempt at doing so is in Test1a.hs, but firstly it requires FlexibleInstances where Test1.hs didn't, and secondly it fails because it can't infer the instance for Bar (Either Int Int) whereas the fundeps version had no problems there. (And yes, this is another cut down example of something I really want to do :-) Cheers, Ganesh