[m-dev.] for review: new module for handling file offsets

[Zoltan Somogyi]

> > That would be a nice goal to shoot for eventually. But right now,
> > that would require lots of changes throughout the compiler, since
> > at the moment we just copy term contexts, and we would need to change
> > that so that in every such place we did something else appropriate.
> > Unless one can show how we can use regions to improve the output we
> > give to users, *and their proposal is implemented*, the work required
> > by those modifications is not justified.
> 
> I thought you were arguing that this was of general utility?

It is. I did not say it was everything anyone could ever ask for reporting
errors. There is no reason to think that the module I have proposed could not
later be extended to handle file regions (and I do mean extended, and not
modified; I don't think the existing code would have to be changed). However,
I think it is better for such extensions to wait until we need them, because
then we will have a better idea of exactly what is required.

Zoltan.