From: Jeremy Yallop <yallop@gmail.com>
To: "Daniel Bünzli" <daniel.buenzli@erratique.ch>
Cc: caml list <caml-list@inria.fr>
Subject: Re: [Caml-list] Stability of order between polymorphic variants
Date: Thu, 5 Sep 2013 10:26:42 +0100 [thread overview]
Message-ID: <CAAxsn=FV00_ky3Zfd8yN9H01fe2wPs5MVpmrPtsyK6M4YYmuQQ@mail.gmail.com> (raw)
In-Reply-To: <EB3B4FB66B1C49E89F3B56664559EFA1@erratique.ch>
On 5 September 2013 01:17, Daniel Bünzli <daniel.buenzli@erratique.ch> wrote:
> The question is, is the order between polymorphic variants an invariant provided by the compiler or is it subject to change ?
The order is fairly unlikely to change. It's based on a hash function
that's used during type checking to determine whether tags can occur
in the same type:
# [`premiums; `squigglier];;
Characters 12-23:
[`premiums; `squigglier];;
^^^^^^^^^^^
Error: Variant tags `premiums and `squigglier have the same hash value.
Change one of them.
Changing the hash function could cause some existing programs to be rejected.
next prev parent reply other threads:[~2013-09-05 9:26 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-05 0:17 Daniel Bünzli
2013-09-05 2:06 ` Anthony Tavener
2013-09-05 2:11 ` Anthony Tavener
2013-09-05 2:18 ` Francois Berenger
2013-09-05 2:31 ` Anthony Tavener
2013-09-05 7:47 ` Stéphane Glondu
2013-09-05 8:24 ` Jacques Garrigue
2013-09-05 8:39 ` Mark Shinwell
2013-09-05 9:26 ` Jeremy Yallop [this message]
2013-09-05 14:46 ` Goswin von Brederlow
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