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From: Jacques Garrigue <garrigue@math.nagoya-u.ac.jp>
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Date: Thu, 24 Mar 2011 09:48:05 +0900
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References: <07EE3576-E5F0-4187-AE8C-DEFEA5C92303@gmail.com> <622E23E3-5614-4ADE-B517-672577A406A2@math.nagoya-u.ac.jp> <EA51F199-538A-486F-ADB0-76BE93B96CB2@gmail.com>
To: Joel Reymont <joelr1@gmail.com>
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Subject: Re: [Caml-list] fighting the type system

On 2011/03/24, at 9:16, Joel Reymont wrote:
>> If you just want the Endpoint interface to specify an object type
>> containing at least write, you could use a private row type:
> 
> The private row type is what I was clearly missing.
> 
> Why does it work with the private row type, though? 

Because if you just define a constrained type every occurrence is
going to be a different instance of this type, while a private row type
ensures that this is the same type throughout the module.

> Are there other uses for 'private' in a module?
> 
> Is the use of private row types described somewhere?

They are described described in section 7.9.3 of the manual:
http://caml.inria.fr/pub/docs/manual-ocaml/manual021.html#toc76

You can find more examples in my paper:
http://www.math.nagoya-u.ac.jp/~garrigue/papers/privaterows-aplas2006.pdf

Cheers,

Jacques Garrigue