From: Alessandro Baretta <alex@baretta.com>
To: caml-list@inria.fr
Cc: Lauri Alanko <la@iki.fi>, Dan Schmidt <dfan@dfan.org>
Subject: Re: [Caml-list] Design advice
Date: Mon, 30 Sep 2002 18:03:24 +0200 [thread overview]
Message-ID: <3D9875CC.5000707@baretta.com> (raw)
In-Reply-To: <20020929122730.GA1093@la.iki.fi>
Lauri Alanko wrote:
> This doesn't help you much, but you may be interested to know that in
> Haskell this wouldn't be much of a problem. You would do simply:
>
> data Suit = Spades | Hearts | Diamonds | Clubs
> deriving (Eq, Ord, Enum, Ix)
>
> ...
> Finally, "Ix" means that the compiler generates some functionality that
> is required for a data type to be usable as an array index. And this is
> probably the feature that you seem to need. In Haskell, you could have
> an array whose _index_ type is Suit. With such an array, there's no fear
> of overflowing, because there simply _aren't_ any index values of the
> proper type that weren't included in the domain of the array.
>
> Of course you can get the same safety in ocaml, too, but it just
> requires some more work on your part.
>
> This isn't an unconditional plug for Haskell, mind you. Both Haskell and
> ocaml are fine languages, and each has great features that the other
> lacks.
>
>
> Lauri Alanko
> la@iki.fi
type tagged_type = Tag1 of foo | Tag2 of bar | ...
class ['a] tagged_array size =
object
val map = Hashtbl.create size
method set index value = Hashtbl.remove map index;
Hashtbl.add map index value
method get index = Hashtbl.find map index
(* any other methods you might need *)
end
It's not really an array, but it's almost as fast and works
very much like one. I think this approach might solve most
of Dan's problems.
Alex
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next prev parent reply other threads:[~2002-09-30 15:53 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-09-27 16:47 Dan Schmidt
2002-09-28 10:48 ` John Prevost
2002-09-28 10:55 ` Chris Hecker
2002-09-28 19:02 ` William Lovas
2002-09-28 22:01 ` John Gerard Malecki
2002-09-28 23:03 ` Chris Hecker
2002-09-30 15:35 ` Kontra, Gergely
2002-09-28 22:46 ` Chris Hecker
2002-09-29 12:27 ` Lauri Alanko
2002-09-30 16:03 ` Alessandro Baretta [this message]
2002-10-01 11:37 ` Xavier Leroy
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