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[Caml-list] extensible records again
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Date: -- (:)
From: Achim Blumensath <blume@l...>
Subject: Re: [Caml-list] extensible records again
Michael Vanier wrote:
> 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?

Yes, it is mentioned in the manual at the end of section 1.5.
The usual syntax is 'b . 'b without the !.

Achim
-- 
________________________________________________________________________
                                                              | \_____/ |
   Achim Blumensath                                          \O/ \___/\ |
   LaBRI / Bordeaux                                          =o=  \ /\ \|
   www-mgi.informatik.rwth-aachen.de/~blume                  /"\   o----|
____________________________________________________________________\___|

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