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Date: Mon, 11 Jul 2005 09:18:30 +0200
From: Remi Vanicat <remi.vanicat@gmail.com>
Reply-To: Remi Vanicat <remi.vanicat@gmail.com>
To: caml-list@inria.fr
Subject: Re: [Caml-list] Object typing
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2005/7/11, Christophe TROESTLER <debian00@tiscali.be>:
[...]

> # class ['a] entity =3D
> object
>   method is_a (v:'a) =3D (v =3D `Entity)
> end;;
>   class ['a] entity :
>   object constraint 'a =3D [> `Entity ] method is_a : 'a -> bool end
>
[...]

> P.S.  Notice the "_" in "_[> `Entity | `Predator ]".  It means that
> the full type is yet to be determined.  Close it before the end of
> your program.

Notice that one can do better than this :
# class [+'a] entity =3D
object
 method is_a (v:'a) =3D (v =3D `Entity)
end;;
     class ['a] entity :
  object constraint 'a =3D [> `Entity ] method is_a : 'a -> bool end
# let e =3D new entity;;
val e : [> `Entity ] entity =3D <obj>

now we don't have an _ type, and there is no need to close it before
the end of the program.

(Ps: sorry Christophe for the private mail, I used the wrong button)