In some languages you don't give field names, just types. You bind fields to names only when pattern matching. For example in Haskell: type Year = Int

In some languages you don't give field names, just types. You bind fields to names only when pattern matching. For example in Haskell: type Year = Int type Month = Int type Day = Int -- fields have no names, just types data Date = Date Year Month Day -- we bind fields to names only when necessary next (Date y 12 31) = Date (y + 1) 1 1 next (Date y m d) | d == daysOf m = Date y (m + 1) 1 | otherwise = Date y m (d + 1) where daysOf = (!!) [0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31] Is something like this what you mean?