From: Andreas Rossberg <rossberg@ps.uni-sb.de>
To: Mark Shinwell <Mark.Shinwell@cl.cam.ac.uk>
Cc: caml-list@inria.fr
Subject: Re: [Caml-list] Type inference question
Date: Tue, 26 Apr 2005 15:41:18 +0200 [thread overview]
Message-ID: <426E44FE.2000003@ps.uni-sb.de> (raw)
In-Reply-To: <20050426131907.GA10841@three-tuns.net>
Mark Shinwell wrote:
>
> However, in the Marshal example above, we have
>
> Marshal.from_channel stdin []
>
> in the first part of the "let". In the SML terminology, this is not a
> "nonexpansive expression"[*] (unlike "fun x -> x"). Therefore, I would
> have thought that the appearance of such an expression here would
> prohibit generalisation (in order to prevent possible unsoundness in the
> presence of mutable state). This is presumably not the case in OCaml:
> can someone explain why?
Recent versions of OCaml employ a slightly relaxed variant of the value
restriction that allows generalising of variables in covariant position,
because that is always safe.
Cheers,
- Andreas
--
Andreas Rossberg, rossberg@ps.uni-sb.de
Let's get rid of those possible thingies! -- TB
next prev parent reply other threads:[~2005-04-26 13:42 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-04-26 11:15 Julien Verlaguet
2005-04-26 12:00 ` [Caml-list] " Jean-Christophe Filliatre
2005-04-26 13:19 ` Mark Shinwell
2005-04-26 13:41 ` Andreas Rossberg [this message]
2005-04-26 13:45 ` Mark Shinwell
2005-04-26 13:54 ` Jacques Garrigue
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