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From: Jon Harrop <jon@jdh30.plus.com>
To: caml-list@inria.fr
Subject: Re: [Caml-list] Phantom types
Date: Mon, 23 Aug 2004 16:16:58 +0100	[thread overview]
Message-ID: <200408231616.58139.jon@jdh30.plus.com> (raw)
In-Reply-To: <200408231049.59342.jon@jdh30.plus.com>

On Monday 23 August 2004 10:49, Jon Harrop wrote:
> Secondly, specifying the types as Markus did (e.g. [> `Even])...

I should add, using:

  val add_even_even : [> `Even ] t -> [> `Even ] t -> [> `Even ] t
  val add_even_odd : [> `Even ] t -> [> `Odd ] t -> [> `Odd ] t

allows:

# PhantomInt.add_even_odd i j;;
val k : _[> `Odd ] PhantomInt.t = <abstr>

which can then be misused:

# PhantomInt.add_even_even i k;;
- : [ `Even ] PhantomInt.t = <abstr>

I think this is because [> `Even] means any superset of [ `Even ] whereas [< 
`Even], which was probably intended, means any subset of [ `Even ]. Indeed, 
the latter appears to work.

Cheers,
Jon.

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  parent reply	other threads:[~2004-08-23 15:20 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2004-07-31  8:56 [Caml-list] const equivalent for mutable types? Christopher A. Gorski
2004-07-31  9:24 ` Jean-Marie Gaillourdert
2004-07-31 10:24   ` Jean-Marie Gaillourdert
2004-07-31 10:50   ` Markus Mottl
2004-07-31 14:31     ` Brian Hurt
2004-07-31 15:51       ` Markus Mottl
2004-07-31 17:05       ` skaller
2004-07-31 10:34 ` Markus Mottl
2004-07-31 13:44   ` Jon Harrop
2004-07-31 16:31     ` [Caml-list] Phantom types Markus Mottl
2004-08-23  9:49       ` Jon Harrop
2004-08-23 12:25         ` [Caml-list] Why does ocaml use custom buffering? Daan Leijen
2004-08-23 15:16         ` Jon Harrop [this message]
2004-08-27  9:03           ` [Caml-list] Phantom types Jacques GARRIGUE
2004-08-25 21:03         ` brogoff
2004-07-31 16:35     ` [Caml-list] const equivalent for mutable types? skaller
2004-07-31 17:23       ` [Caml-list] Functional arrays Jon Harrop
2004-07-31 18:45         ` skaller
2004-08-02  5:07           ` brogoff
2004-08-02  7:45         ` Diego Olivier Fernandez Pons
2004-08-05 16:42           ` Daniel Ortmann
2004-08-05 17:02             ` Diego Olivier Fernandez Pons
2004-08-05 17:16             ` Diego Olivier Fernandez Pons
2004-07-31 17:45   ` [Caml-list] const equivalent for mutable types? Chris Gorski
2004-07-31 14:11 ` Brian Hurt
2010-05-17 14:59 Phantom types Thomas Braibant
2010-05-17 16:37 ` [Caml-list] " Goswin von Brederlow

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