[m-dev.] Re: for review: new method of handling failures, part 1 of 6

[Zoltan Somogyi]

> > I don't know the reason. I suppose we could reverse the order, see what
> > breaks, and document that :-(
> 
> Well, goal_info.m has a slightly more detailed comment:
> 
>  % ... Note that when traversing forwards
>  % through a goal, deaths must be applied before births;
>  % this is necessary to handle certain circumstances where a
>  % variable can occur in both the post-death and post-birth sets,
>  % or in both the pre-death and pre-birth sets.

Yes, but this doesn't say what those circumstances are, which is the crux
of the issue.

>> The design above requires the allocation and filling of only a one-word cell;
> 
> Does it even require that?  Won't the position_info be a `no_tag' type
> for which there is no runtime overhead at all?

Yes, you are right. I always forget about no_tag, perhaps because I didn't
design it :-)

Zoltan.