caml-list - the Caml user's mailing list
 help / color / mirror / Atom feed
From: Guillaume Yziquel <guillaume.yziquel@citycable.ch>
To: Alain Frisch <alain@frisch.fr>
Cc: caml-list <caml-list@inria.fr>
Subject: Re: [Caml-list] Re: module typing issue
Date: Mon, 28 Mar 2011 12:33:25 +0200	[thread overview]
Message-ID: <20110328103325.GH20598@localhost> (raw)
In-Reply-To: <4D903E90.4080907@frisch.fr>

Le Monday 28 Mar 2011 à 09:53:52 (+0200), Alain Frisch a écrit :
> On 03/25/2011 08:01 PM, Guillaume Yziquel wrote:
> >type error = private int
> >
> >external get_error : unit ->  error = "zzz"
> >
> >You get some error level that you can pattern match as an int, and this
> >also enforces that all values of type error come from a call to
> >get_error.
> 
> You need to coerce explicitly from type error to type int (... :>
> int), so this is not really different from defining error as an
> abstract type and exposing a function error->int.
> 
> -- Alain

Yes, doesn't work for private ints. However, it works for stuff like
that, though it's not exactly the same thing as a 'private int':

# type t = private A | B;;
type t = private A | B
# let x : t = Obj.magic 0;;
val x : t = A
# match x with A -> true | _ -> false;;
- : bool = true
# A;;
Error: Cannot create values of the private type t

I thought it also worked on for ints, and in a sense, I'm surprised that
you cannot pattern match private ints as ints without a coercion.

So for enumerating errors coming from C stubs, you can still do it this
way.

-- 
     Guillaume Yziquel


  reply	other threads:[~2011-03-28 11:13 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-03-25  8:34 [Caml-list] " Joel Reymont
2011-03-25  8:44 ` [Caml-list] " Joel Reymont
2011-03-25 14:17   ` Joel Reymont
2011-03-25 15:46     ` Andreas Rossberg
2011-03-25 15:57       ` Joel Reymont
2011-03-25 16:04         ` Andreas Rossberg
2011-03-25 16:42       ` Guillaume Yziquel
2011-03-25 16:59         ` Andreas Rossberg
2011-03-25 19:01           ` Guillaume Yziquel
2011-03-25 19:13             ` Andreas Rossberg
2011-03-28  7:53             ` Alain Frisch
2011-03-28 10:33               ` Guillaume Yziquel [this message]
2011-03-28 11:29                 ` David Allsopp
2011-03-28 11:58                   ` Guillaume Yziquel
2011-03-28 12:11                     ` David Allsopp
2011-03-28 12:29                       ` Guillaume Yziquel
2011-03-28 12:23                     ` Alain Frisch
2011-03-28 12:39                       ` Guillaume Yziquel
2011-03-28 11:32               ` David Allsopp
2011-03-28 12:02                 ` Guillaume Yziquel

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20110328103325.GH20598@localhost \
    --to=guillaume.yziquel@citycable.ch \
    --cc=alain@frisch.fr \
    --cc=caml-list@inria.fr \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).