From: Julien Signoles <Julien.Signoles@lri.fr>
To: Johannes Kanig <johannes.kanig@lri.fr>
Cc: caml-list@inria.fr
Subject: Re: [Caml-list] polymorphic variants and promotion
Date: Tue, 19 Feb 2008 13:38:38 +0100 (CET) [thread overview]
Message-ID: <Pine.LNX.4.63.0802191330150.23713@serveur9-10.lri.fr> (raw)
In-Reply-To: <926565e50802190223r456d0ec2we4b8a4f51b134f42@mail.gmail.com>
Hello Johannes,
> What I don't understand is why the promotion of [`A of int] to [> `A of int]
> is not possible in general:
>
> # `A 1;;
> - : [> `A of int ] = `A 1
> # (`A 1 : [`A of int]) ;;
> - : [ `A of int ] = `A 1
> # ((`A 1 : [`A of int]) : [> `A of int]) ;;
> - : [ `A of int ] = `A 1
>
> Does anyone have an answer?
You have to use coercion in order to promote:
# (`A 1 : [ `A of int ] :> [> `A of int ]);;
- : [> `A of int ] = `A 1
--
Julien
next prev parent reply other threads:[~2008-02-19 12:38 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-02-19 10:23 Johannes Kanig
2008-02-19 12:38 ` Julien Signoles [this message]
2008-02-19 13:37 ` [Caml-list] " Keiko Nakata
2008-02-19 22:26 ` Christophe Raffalli
2008-02-20 4:50 ` Jacques Garrigue
2008-02-19 12:48 ` Remi Vanicat
2008-02-20 5:01 ` [Caml-list] " Jacques Garrigue
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