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Create a constraint between variant type and data list
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| Date: | -- (:) |
| From: | Sylvain Le Gall <sylvain@l...> |
| Subject: | Create a constraint between variant type and data list |
Hello all,
I would like to somehow enforce that a variant type is associated with
an entry in a data list.
For example,
I would like to define:
type license = GPL | LGPL
and
let data = [ GPL, "GNU Public license";
LGPL, "GNU Lesser General Public license" ]
I would like to enforce that all variants of license are in the
association list.
I have tried to use polymorphic variants, but don't see how to enforce
this constraint.
The point, is that if I add a new variant to license (e.g. BSD3), the
compiler output an error because this new variant is not in data list.
Any ideas ? If you need to use another type expression rather than
variant, please do so, as long as I am able to link the license type
and data list.
Thanks all,
Sylvain Le Gall