From mboxrd@z Thu Jan  1 00:00:00 1970
Received: (from weis@localhost) by pauillac.inria.fr (8.7.6/8.7.3) id XAA16496 for caml-red; Sun, 8 Oct 2000 23:10:39 +0200 (MET DST)
Received: from concorde.inria.fr (concorde.inria.fr [192.93.2.39]) by pauillac.inria.fr (8.7.6/8.7.3) with ESMTP id WAA15455 for <caml-list@pauillac.inria.fr>; Sun, 8 Oct 2000 22:07:34 +0200 (MET DST)
Received: from isil.localdomain (adsl-151-201-232-68.bellatlantic.net [151.201.232.68])
	by concorde.inria.fr (8.10.0/8.10.0) with ESMTP id e98K7XX21523
	for <caml-list@inria.fr>; Sun, 8 Oct 2000 22:07:33 +0200 (MET DST)
Received: by isil.localdomain (Postfix, from userid 1000)
	id F2FFE37655; Sun,  8 Oct 2000 16:09:22 -0400 (EDT)
To: Julian Assange <proff@iq.org>
Cc: caml-list@inria.fr
Subject: Re: polymorphic variant oddity
References: <wxitr4naws.fsf@suburbia.net>
From: John Prevost <jmp@arsdigita.com>
Date: 08 Oct 2000 16:09:22 -0400
In-Reply-To: <wxitr4naws.fsf@suburbia.net>
Message-ID: <87lmvzjdsd.fsf@localhost.localdomain.>
User-Agent: Gnus/5.0808 (Gnus v5.8.8) Emacs/20.7
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Sender: weis@pauillac.inria.fr

>>>>> "ja" == Julian Assange <proff@iq.org> writes:

  ja> Unbound value x
  ja> # let `F x = 1;;
  ja> This expression has type int but is here used with type [< `F of 'a | ..]
  ja> # let `F x = `F 1;;
  ja> val x : int = 1
  ja> # `F 4;;
  ja> - : [> `F of int] = `F 4

  ja> What exactly is the meaning this?

Looks like normal pattern matching to me:


# let Some x = x;;
Unbound value x
# let Some x = 1;;
This expression has type int but is here used with type 'a option
# let Some x = Some 1;;
Warning: this pattern-matching is not exhaustive.
Here is an example of a value that is not matched:
None
val x : int = 1
# Some 4;; 
- : int option = Some 4

What did you expect to happen?

John.