Inheritance and overloading using data Object and w\o typeclasses

dummyInheritance.hs

import Text.Printf (printf)

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{-| Datatype for all the objects -}
data Object t =
  Object { getA :: Int -- common fields for all the objects
         , setA :: Int -> Object t -- setter example
         , action1 :: IO () -- generally speaking, action is just a regular object field
         , objectType :: t
         }


{-| Object factory.
    It`s supposed that this function will not be used directly,
    but only for creating a new sub-objects. -}
object a action_1 t =
  Object { getA = a
         , setA = \a' -> object a' action_1 t
         , action1 = action_1
         , objectType = t
         }

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type Object1 = Object Object1Type
data Object1Type = Object1Type -- specific object1-fields only could be here

object1 a = object a action_1 Object1Type
  where
    action_1 = printf "object1 with field %d \n" a

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type Object2 = Object Object2Type
data Object2Type = Object2Type

object2 o = object (getA o) action_1 Object2Type -- note that we inherit the existing object
  where
    action_1 = do -- overloading
      print "object2 and..."
      action1 o -- super action

-- of course we could also construct the new object1 dynamically:
{- object2 a =
  let o        = object1 a
      a'       = getA o
      action_1 = do
        print "object2 and..."
        action1 o
  in object a' action_1 Object2Type -}
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main = do
  let o1 = object1 10
      o2 = object2 o1
  action1 o1
  action1 o2