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Message-ID: <4B27BBB4.50006@bardou.fr>
Date: Tue, 15 Dec 2009 17:39:16 +0100
From: Romain Bardou <romain@bardou.fr>
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To: caml-list <caml-list@yquem.inria.fr>
Subject: Module abbreviation
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X-Spam: no; 0.00; abbreviation:01 mli:01 abbreviation:01 link-time:01 cmo:01 ast':01 mli:01 sig:01 sig:01 caml-list:01 undefined:01 ast:02 ast:02 renaming:02 toto:02 

Hello, dear Caml-list,

I have a file ast.mli. It has no .ml implementation as it contains only
type definitions.

I have a file toto.ml, which contains simply:

module A = Ast

So I only use it as an abbreviation, to write A.t instead of Ast.t for
instance.

However, at link-time, the following error occurs:

File "_none_", line 1, characters 0-1:
Error: Error while linking toto.cmo:
Reference to undefined global `Ast'

I found a workaround, which is to change ast.mli to put all type
definitions in a signature, such as:

module type Sig =
sig
  type t = ...
  ...
end

And then, in toto.ml:

module type A =
sig
  include Ast.Sig
end

Is there any better way to write such a module abbreviation, without
changing ast.mli? And, of course, without copying or renaming ast.mli
into ast.ml.

By the way, this is yet another evidence for the need of a construction
"sig of" which would take a module (with or without implementation) and
return its signature.

Thanks,

-- 
Romain Bardou