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typing problem with sexplib and mutually recursive polymorphic types
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Date: -- (:)
From: Yitzhak Mandelbaum <yitzhakm@C...>
Subject: Re: [Caml-list] typing problem with sexplib and mutually recursive polymorphic types
While I'm not sure it will help you in this case (because the code is  
generated), I should note that type *inference* for polymorphic  
recursion is undecidable, but type *checking* is not. Moreover, its  
pretty easy to do in OCaml (if a bit clunky).

An earlier discussion on this list covered a number of ways to do it.  
Here's one:

http://groups.google.com/group/fa.caml/msg/d85e3f62dd52d365

Cheers,
Yitzhak


On Mar 11, 2009, at 10:20 AM, Markus Mottl wrote:

> On Wed, Mar 11, 2009 at 02:11, yoann padioleau <padator@wanadoo.fr>  
> wrote:
>> Yes on this example, but what if I can't move it out because
>> the types really need to be mutually recursive ?
>
> I'm afraid, I don't see any straightforward way of achieving this
> goal.  If the above were allowed in a truly recursive way, you'd
> essentially end up with polymorphic recursion, which is undecidable.
>
> Regards,
> Markus
>
> -- 
> Markus Mottl        http://www.ocaml.info         
> markus.mottl@gmail.com
>
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-----------------------------
Yitzhak Mandelbaum