Sill I want to make objects packed with their objects and functions. Doesn't mean that I have to use existential data types?
Only if you need to hide the type of the object. If you don't need to hide the type then Haskell's typeclasses give you (what I understand of) what you want. I can write polymorphic functions which take an arbitrary type of object and invoke methods like ==, + and show (say) on it. foo :: (Eq a, Num a) => a -> String foo x = if x == 0 then "" else show (x+1) Actually, I suspect this is not quite what you want but the word 'object' has been used by so many people to mean so many things that it's only by throwing out strawmen like Haskell's typeclasses that we can understand what you actually do mean. -- Alastair Reid alastair@reid-consulting-uk.ltd.uk Reid Consulting (UK) Limited http://www.reid-consulting-uk.ltd.uk/alastair/