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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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