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Date: -- (:)
From: Michael Vanier <mvanier@c...>
Subject: Re: [Caml-list] extensible records again

Achim,

I took up your suggestion and downloaded your code.  In Opaque.ml I see
this mysterious declaration:

type opaque 'a =
{
  data      : !'b . 'b;
  type_info : type_info 'a
}
and type_info 'a =
{
  apply   : opaque 'a -> 'a -> 'a;
  compare : opaque 'a -> opaque 'a -> bool;
  unify   : opaque 'a -> opaque 'a -> bool
};
 
I realize that this uses the revised syntax, but I can't find any
documentation on what "!'b . 'b" is supposed to mean.  It looks like a
universal quantifier on 'b -- correct?

Mike

> Date: Mon, 22 Mar 2004 09:13:55 +0100
> From: Achim Blumensath <blume@labri.fr>
> Mail-Followup-To: caml-list@inria.fr
> 
> Michael Vanier wrote:
> > I've written a dynamically-typed language in ocaml, and I want to be able to
> > add new types to the language without having to add new primitive types to
> > the system.
> 
> This weekend I have done something like this in ant:
> 
>    www-mgi.informatik.rwth-aachen.de/~blume/pub/ant-current.tar.bz2
> 
> The type declarations are in
> 
>   VM/Types.ml  and  VM/Opaque.ml
> 
> and an example showing how to define your own type in
> 
>   Markup/ALBindings.ml
> 
> Achim
> -- 
> ________________________________________________________________________
>                                                               | \_____/ |
>    Achim Blumensath                                          \O/ \___/\ |
>    LaBRI / Bordeaux                                          =o=  \ /\ \|
>    www-mgi.informatik.rwth-aachen.de/~blume                  /"\   o----|
> ____________________________________________________________________\___|
> 
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