[Haskell-cafe] Re: Designing an object model in Haskell (RESOLVED)

13 Dec 2006

      Hi all,

I'm now using existential types.  I avoided learning about them because the
name sounded so highly technical and obscure it did not occur to me they
could be related to OO.

Thanks,

-John

On 12/7/06, John Ky  wrote:
...
Hi,
I've got an object model that I have a difficult time conceptualising how
it might look like in Haskell:
class Element { }
class Inline : Element { }
class ParentInline : Inline {
   List<Inline> children;
}
class Bold : ParentInline { }
class Underline : ParentInline { }
class Link : ParentInline {
   String link;
}
class Text : Inline {
   String text;
}
class Block : Element { }
class Paragraph : Block {
   List<Inline> paragraph;
}
class Heading : Block {
   List<Inline> heading;
}
class Document : Element {
   List<Block> blocks;
}
How best to represent this OO data model in Haskell?
Thanks
-John