From: William Chesters <williamc@dai.ed.ac.uk>
To: caml-list@inria.fr
Subject: Re: Proposal for study: Add a categorical Initial type to ocaml
Date: Sun, 10 Oct 1999 22:05:26 +0100 [thread overview]
Message-ID: <24984.199910102105@buckie> (raw)
In-Reply-To: <38002EBF.DF0EF779@maxtal.com.au>
skaller writes:
> > > Boxed values can use a null pointer for none.
> >
> > I have a question--how is this different (except for the efficiency of
> > using null) from using a 'a option array?
>
> It isn't, in theory, it is exactly the same (and therefore sound).
I think (correct me if I'm wrong, sorry) that this is a return to an
issue which seems to be a bit of an FAQ.
The problem is that if you have a value of the type `int option
option', you have to be able to distinguish between `None' and `Some
None'! If both the enumeration-indirections are elided, you can't; if
only one of them is, you have inconsistency which would presumably
have to be resolved using whole-program optimisation or something.
For the lowdown and an interesting proposal for a fix, see
http://caml.inria.fr/caml-list/0967.html
The same idea would obviously apply to arrays.
next prev parent reply other threads:[~1999-10-10 21:34 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
1999-10-06 13:25 Stdlib regularity Ohad Rodeh
1999-10-06 16:18 ` Markus Mottl
1999-10-08 14:06 ` Matías Giovannini
1999-10-10 20:09 ` Pierre Weis
1999-10-10 20:12 ` Matías Giovannini
1999-10-08 14:10 ` skaller
1999-10-08 19:21 ` Markus Mottl
1999-10-09 21:14 ` Dave Mason
1999-10-06 18:50 ` John Prevost
1999-10-07 7:33 ` skaller
1999-10-07 9:18 ` Francisco Valverde Albacete
1999-10-08 14:56 ` skaller
1999-10-09 22:26 ` Francois Rouaix
1999-10-10 5:38 ` skaller
1999-10-10 20:44 ` William Chesters
1999-10-10 21:43 ` Hongwei Xi
1999-10-11 0:36 ` skaller
1999-10-12 7:20 ` David Mentr{'e}
1999-10-08 16:38 ` Proposal for study: Add a categorical Initial type to ocaml skaller
1999-10-09 22:43 ` John Prevost
1999-10-10 3:18 ` chet
1999-10-10 6:14 ` skaller
1999-10-10 21:05 ` William Chesters [this message]
1999-10-10 22:36 ` chet
1999-10-10 22:38 ` chet
1999-10-11 19:30 ` John Prevost
1999-10-12 8:34 ` Option types and O'Labl merger Jacques Garrigue
1999-10-12 14:38 ` William Chesters
1999-10-13 5:35 ` Frank A. Christoph
1999-10-13 8:48 ` Jacques Garrigue
1999-10-11 0:51 ` Proposal for study: Add a categorical Initial type to ocaml skaller
1999-10-11 12:40 ` John Prevost
1999-10-12 19:20 ` skaller
1999-10-12 11:33 ` Jean-Francois Monin
1999-10-10 16:10 ` chet
1999-10-10 18:52 Vyskocil Vladimir
1999-10-12 15:33 Damien Doligez
1999-10-12 15:44 Damien Doligez
1999-10-13 16:42 Manuel Fahndrich
1999-10-14 22:43 ` skaller
1999-10-14 23:16 Manuel Fahndrich
1999-10-17 9:18 ` skaller
1999-10-18 16:48 Manuel Fahndrich
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