G :: Type = data male | female
  
MaleNames :: Type  = data Tom | Jim
FemaleNames :: Type = data Jill | Sara

Name (g:: G)
     :: Type
     = case g of {
         (male) -> MaleNames;
         (female) -> FemaleNames;}


select :: (g:: G) -> Name g
       = \(g::G) -> case g of {
                      (male) -> Tom@_;
                      (female) -> Jill@_;}