From: Warren Harris <warrensomebody@gmail.com>
To: Mauricio Fernandez - mfp@acm.org
<+caml+warren+dfcc5fe769.mfp#acm.org@spamgourmet.com>
Cc: caml-list@inria.fr
Subject: Re: [Caml-list] polymorphic variants and recursive functions (caml: to exclusive)
Date: Wed, 25 Mar 2009 17:06:51 -0700 [thread overview]
Message-ID: <1E1BE32F-DAB2-4942-B266-42430F8AA37E@gmail.com> (raw)
In-Reply-To: <20090325232438.GW8986@NANA.localdomain>
Mauricio,
Thanks for your response...
On Mar 25, 2009, at 4:24 PM, Mauricio Fernandez - mfp@acm.org wrote:
> The Lwt.t type is abstract and invariant since no annotation has
> been given
> for the type variable (you'd need it to be type +'a t):
>
...
>
> Unfortunately, the type variable is in both variant and
> contravariant position
> in the definition of Lwt.t...
Just to be sure I understand you... you're saying due to the
definition/implementation of Lwt and the fact that the type parameter
cannot be declared covariant, that what I'm trying to do with phantom
types just can't work in this case. I was afraid of that. :-(
Warren
prev parent reply other threads:[~2009-03-26 0:06 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-03-25 21:39 polymorphic variants and recursive functions Warren Harris
2009-03-25 23:24 ` [Caml-list] " Mauricio Fernandez
2009-03-26 0:06 ` Warren Harris [this message]
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