I'm coming from the OO world and trying to adapt. I've noticed that if I declare two types like this data Thing1 = Thing1 { itemPos :: Int } data Thing2 = Thing2 { itemPos :: Int } then I get the error "Multiple declarations of Main.itemPos" However, I can successfully do this: type Pos = ( Int, Int ) type Dimension = ( Int, Int, Int, Int ) data LayoutItem = StaffItem { itemPos :: Pos, itemDim :: Dimension } | TextItem { itemPos :: Pos, itemDim :: Dimension } d1 = TextItem ... d2 = StaffItem ... i1 = itemPos d i2 = itemPos d2 This seems to define itemPos in a way that can sense whether it's dealing with a StaffItem-type LayoutItem or a TextItem-type LayoutItem. I don't know if this would be considered an overloaded operator. However, it does resemble derived class in OO. For that matter, I don't know what the term is for a "StaffItem-type LayoutItem". The type is clearly LayoutItem. "StaffItem" is the constructor. How do you refer to the concept of a LayoutItem constructed via a StaffItem? Again, StaffItem and TextItem resemble derived classes in OO. Any clarification welcome. -Mike