From: Jacques Carette <carette@mcmaster.ca>
To: Dario Teixeira <darioteixeira@yahoo.com>
Cc: caml-list@yquem.inria.fr
Subject: Re: [Caml-list] Width subtyping
Date: Fri, 29 May 2009 10:21:11 -0400 [thread overview]
Message-ID: <4A1FEF57.1080905@mcmaster.ca> (raw)
In-Reply-To: <327446.80988.qm@web111511.mail.gq1.yahoo.com>
Dario Teixeira wrote:
> In other words, polymorphic variants provide a very elegant solution for subtyping
> with sum types. Is there some brilliant idea that could do the same for product types?
>
The dual of sums is products. Open (labelled) sums are "polymorphic
variants". Their duals are open (labelled) products are "rows" (which
O'Caml already supports, through its objects).
See TAPL for a nice introduction to the type theory of labelled records
with subtyping (i.e. rows).
Jacques
PS: note that O'Caml's products are positional while its sums are
labelled, so the duality present in the theory isn't as clear there.
The better dual for O'Caml's sums is really records.
next prev parent reply other threads:[~2009-05-29 14:22 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-05-29 14:10 Dario Teixeira
2009-05-29 14:21 ` Jacques Carette [this message]
2009-05-29 14:43 ` [Caml-list] " David Allsopp
2009-05-29 15:33 ` Richard Jones
2009-05-29 15:38 Dario Teixeira
2009-05-29 15:45 Dario Teixeira
2009-05-29 16:06 ` Till Varoquaux
2009-05-29 15:50 Dario Teixeira
2009-05-30 15:36 Dario Teixeira
2009-05-31 5:18 ` Dave Benjamin
2009-05-31 7:34 ` David Allsopp
2009-06-01 4:21 ` Jacques Garrigue
2009-05-31 23:08 Dario Teixeira
2009-06-01 11:34 ` Yaron Minsky
2009-06-01 13:56 Dario Teixeira
2009-06-01 14:21 ` David Allsopp
2009-06-01 17:04 ` Peng Zang
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