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[Caml-list] Dynamic types, casts, and rights amplification
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Date: -- (:)
From: Markus Mottl <markus@m...>
Subject: Re: [Caml-list] Dynamic types, casts, and rights amplification
On Wed, 11 Jul 2001, Francois Pottier wrote:
> The first one generates exceptions dynamically and uses them as
> tags. The fact that they are exceptions is irrelevant; what matters
> is the ability to generate new tags at runtime. Unfortunately, this
> piece of code isn't accepted by O'Caml, because it doesn't recognize
> the type variable 'a in the exception declaration as bound by the
> preceding type annotation.

I also mentioned this limitation only a few days ago ("polymorphic"
exceptions - they are not really polymorphic, of course, but make use
of type variables bound elsewhere).  Unfortunately, I didn't get any
response so far whether there are inherent difficulties in implementing
an extension. It wouldn't require any syntax change at all, won't break
old code, but clearly gives more expressiveness to the developer. Any

Markus Mottl

Markus Mottl                                   
Austrian Research Institute
for Artificial Intelligence        
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