From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <berenger@riken.jp>
X-Original-To: caml-list@sympa.inria.fr
Delivered-To: caml-list@sympa.inria.fr
Received: from mail1-relais-roc.national.inria.fr (mail1-relais-roc.national.inria.fr [192.134.164.82])
	by sympa.inria.fr (Postfix) with ESMTPS id 956577F249
	for <caml-list@sympa.inria.fr>; Tue, 30 Oct 2012 01:44:06 +0100 (CET)
Received-SPF: None (mail1-smtp-roc.national.inria.fr: no sender
  authenticity information available from domain of
  berenger@riken.jp) identity=pra; client-ip=134.160.33.175;
  receiver=mail1-smtp-roc.national.inria.fr;
  envelope-from="berenger@riken.jp";
  x-sender="berenger@riken.jp"; x-conformance=sidf_compatible
Received-SPF: Pass (mail1-smtp-roc.national.inria.fr: domain of
  berenger@riken.jp designates 134.160.33.175 as permitted
  sender) identity=mailfrom; client-ip=134.160.33.175;
  receiver=mail1-smtp-roc.national.inria.fr;
  envelope-from="berenger@riken.jp";
  x-sender="berenger@riken.jp"; x-conformance=sidf_compatible;
  x-record-type="v=spf1"
Received-SPF: Pass (mail1-smtp-roc.national.inria.fr: domain of
  postmaster@postman.riken.jp designates 134.160.33.175 as
  permitted sender) identity=helo; client-ip=134.160.33.175;
  receiver=mail1-smtp-roc.national.inria.fr;
  envelope-from="berenger@riken.jp";
  x-sender="postmaster@postman.riken.jp";
  x-conformance=sidf_compatible; x-record-type="v=spf1"
X-IronPort-Anti-Spam-Filtered: true
X-IronPort-Anti-Spam-Result: Au8AAKYij1CGoCGvl2dsb2JhbABEwywBAQEBAQgWBzuCXUA9FhgDAgECAUsNCAEBiAKaYJETkBySUgOIV40dhWmNVw
X-IronPort-AV: E=Sophos;i="4.80,675,1344204000"; 
   d="scan'208";a="179455688"
Received: from postman3.riken.jp (HELO postman.riken.jp) ([134.160.33.175])
  by mail1-smtp-roc.national.inria.fr with ESMTP; 30 Oct 2012 01:43:46 +0100
Received: from postman.riken.jp (postman3.riken.jp [127.0.0.1])
	by postman.riken.jp (Postfix) with SMTP id 31C1938380DE
	for <caml-list@inria.fr>; Tue, 30 Oct 2012 09:43:42 +0900 (JST)
Received: from [172.27.98.103] (rikad98.riken.jp [134.160.214.98])
	by postman.riken.jp (Postfix) with ESMTPA id F2D8E382021D
	for <caml-list@inria.fr>; Tue, 30 Oct 2012 09:43:41 +0900 (JST)
Message-ID: <508F22BD.7010103@riken.jp>
Date: Tue, 30 Oct 2012 09:43:41 +0900
From: Francois Berenger <berenger@riken.jp>
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:16.0) Gecko/20121011 Thunderbird/16.0.1
MIME-Version: 1.0
To: caml-list <caml-list@inria.fr>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
X-PMX-Version: 5.6.0.2009776, Antispam-Engine: 2.7.2.376379, Antispam-Data: 2012.10.30.3324
Subject: [Caml-list] Why should I use .mli files?

Hello,

Here is my stupid question of the day:
what's the use of those .mli files?

Is it just to separate interface from implementation
so that the implementation of a module can be changed
without clients of its interface to have to bother?

Does it make compilation of large software faster
by allowing for more parallelization and maybe later on avoiding to 
recompile some parts?

Usually I program in a pure functional style, so my modules
don't carry an internal state.
I feel like "if someone want to re-use a function, so be it".
If I really want to hide a function that I am afraid people
may call in an incorrect manner, I declare it internally
to some public function and use it correctly.

Also, maybe I only work on toy-size OCaml projects. So, I never 
bothrered to create any .mli file.
I would like to know if I should bother about them.

Thanks a lot,
Francois.