Re: Hashing, and Ted's concerns about wastefulness

Ted wrote (quoting Graham)

> > >... we also
> > >need to specify exactly what you get if you retrieve h.<URI>.
> >
> > I think that what you get is a copy of the hashed feature expression.
> 
> Yes, but we need to specify exactly how that is represented.  Remember
> that most hashes on files care about every bit of whitespace and every
> control character; if we don't specify the representation very well,
> we will end up with conflicting hashes on equivalent feature expressions.

How bad a problem is this? Is it is worth trying to assign the same
hash values to differently-represented-but-ultimately-equivalent
feature sets? It is a feature, but it adds complexity to the
specification and to each implementation.

Do you anticipate a pattern of usage where this feature would 
significantly increase efficiency?

> > I'd be happy to have a go at the (h.<URI2>="<hash>") proposal, if that
> > doesn't pre-empt anything that Bill is planning.  I would be more
> > comfortable if we had some consensus on scenarios and goals so that it can
> > be seen to address the perceived problem.
> >
> > #g
> 
> Any concrete proposal would be good, and two may well be better at this
> early stage.

Currently I'm inclined to just put my original proposal, modulo
incremental corrections and cleanups, into Internet Draft form.
However, I'll be rereading and rethinking the discussion at least one
more time before I make my proposal, so my thinking might change.

I'd be happy to see a concrete form of the h.<URI2>="<hash>" proposal
from Graham, or any other counterproposal from anyone else for that
matter, whether I'm pre-empted or post-empted.

  Bill Newman
  [email protected]