From: Jacques Carette <carette@mcmaster.ca>
To: Till Varoquaux <till@pps.jussieu.fr>
Cc: caml-list@inria.fr
Subject: Re: [Caml-list] Why is this allowed?
Date: Mon, 31 May 2010 11:54:14 -0400 [thread overview]
Message-ID: <4C03DBA6.8020208@mcmaster.ca> (raw)
In-Reply-To: <AANLkTilMuMbRly7ZhDt97tZyvkzATpv4_eT0Zwub4hq9@mail.gmail.com>
Nice trick - but my 'problem' [1] regards arbitrary valid OCaml code and
how to serialize code values. The issue seems to be that one needs to
attach an arbitrarily large typing environment to each part of a value,
as there is no global typing environment which will do the job (because
of shadowing).
Jacques
[1] Actually 'our' problem, in that this arose from some issues in
metaocaml, and I am working with Oleg to figure out what is going on.
Interestingly, this never arose in 3.09 and before.
Till Varoquaux wrote:
> AFAIK you are allowed to shadow just about anything in
> implementations. If you wanted to keep the exact same interface but
> retain the ability to avvoid the shadowing issue on the labels you
> could do:
>
> module Foo = struct
> type t = Foo
> end
> type foo = Foo.t = Foo
>
> module Foo2 = struct
> type t = Foo | Bar
> end
>
> type foo2 = Foo2.t = Foo | Bar
>
> HTH,
> Till
>
> On Mon, May 31, 2010 at 10:46 AM, Jacques Carette <carette@mcmaster.ca> wrote:
>
>> type foo = Foo
>> let x = Foo
>>
>> type foo2 = Foo | Bar
>> let y = Foo
>> let z = (x,y) ;;
>>
>> I thought that re-using of algebraic labels was not allowed - but apparently
>> it is? Note that this means that it is impossible to "text" print such
>> structures and hope to recover them uniquely. This also causes very subtle
>> issues when Marshal'ing, and grave issues for code generation [think
>> metaocaml].
>>
>> Jacques
>>
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>
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next prev parent reply other threads:[~2010-05-31 15:54 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-05-31 14:46 Jacques Carette
2010-05-31 15:06 ` [Caml-list] " Lukasz Stafiniak
2010-05-31 15:48 ` Jacques Carette
2010-05-31 15:43 ` Till Varoquaux
2010-05-31 15:54 ` Jacques Carette [this message]
2010-06-09 15:11 ` Goswin von Brederlow
2010-06-09 15:17 ` bluestorm
2010-06-09 15:31 ` Jacques Carette
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