Re: [Caml-list] mutually dependent class and type

[Martin Jambon <martin.jambon@ens-lyon.org>]

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On Fri, 26 Sep 2008, Sébastien Hinderer wrote:

> Dear list,
>
> Is there a (clean) way to define simultaneously a class and a type that
> are mutually recursive ?

I don't think so, but you don't have to.

> Something like this :
> class element (c : content) =
> object
>  ...
> end and type content =
>  | Data of string
>  | Elements of element list;;
>
> This is of course not a valid OCaml definition, but is there a way to
> express it ?

With each class comes a type of the same name. Such type can also be 
defined independently from the notion of class. It is syntactically like 
a record with angle brackets:

type element =
     < content : content >

and content =
     Data of string
   | Elements of element list;;

class element_class (c : content) =
object
   method content = c
end


# new element_class (Elements [ new element_class (Data "abc") ]);;
- : element_class = <obj>


Martin

> Many thanks in advance for your help,
> Sébastien.
>
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