Re: [Caml-list] ocaml and named constants

[Brian Rogoff <bpr@best.com>]

On Thu, 31 May 2001, Luc Maranget wrote:
> But I have another remark
> as far a ``manifest constants'' are the issue, Polymorphic
> variants
> (http://caml.inria.fr/ocaml/htmlman/manual003.html)
> seem to do the job.
> 
> After all, provided you do not care much about the actual value of Foo)

Ah, the problem for me is that I really do care about the actual value for 
the constants. It turns out that I may process binary file formats (GDSII
is the canonical example) where I want the name to correspond to a number. 
Of course, I can and do do it by hand (or use P4) by writing the equivalent of 
Ada's 'Pos and 'Val attributes for enumerated types. I would use plain old 
sum types too since I don't need them to be open for extension. It's a bit 
more cumbersome than I'd like it since I have to specify the mapping twice 
(constructor -> integer and integer -> constructor) which is cumbersome.

-- Brian


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