Proposal for Requiring Save/Restore of Sets and Tags

[Carl Ollivier-Gooch]

On 10/04/2010 09:29 PM, Mark Miller wrote:
> Hi Carl,
>
> I don't think I disagree with anything you've said.
>
> But, if the spec. says cycles are NOT allowed and an implementation
> supports that, I don't see how that is a problem.
>
> So, maybe the whole issue is mentioning the issue of cycles as
> prominently as they are in the proposal.
>
> Now, if the spec. says cycles ARE ALLOWED and an implementation does NOT
> support that, then that would be a problem.

Agreed, throughout.  But we probably should decide once and for all what 
we intend about cycles (and put in the docs this time...).

> But, I think you are arguing that the spec. should NOT include cycles. I
> kinda agree with that as they really don't seem to make sense. The only
> use case I can think of is improper subsets where some implementation
> wants to be a little lazy about detecting outright equality between
> subsets where it might otherwise easily decide its ok to make one a
> subset of another.

To get a cycle, you've got to have this looping back on itself. 
Semantically, it makes sense, but it's (a) silly and (b) unlikely to 
occur except on purpose, in which case, why bother?

Carl

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Dr. Carl Ollivier-Gooch, P.Eng.                   Voice: +1-604-822-1854
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