[Hat] Proposal, Heirarchical module structure for tools

[Neil Mitchell]

Hi

> Yes, it matters a great deal.  We have reserved the 'Hat' top-level
> namespace for the exclusive use of trace-transformed programs.  No-one
> should ever use that namespace intentionally for anything else.

Fair enough, seems reasonable. Although then I wonder if we need the
"Hat" part, just Tracing.Observe should be enough, since its just as
unique, and its in the Hat repo so makes it clear enough.

> My suggestion would be just to drop that part.  So, e.g.
>
>    Tracing.Hat.Observe
>    Tracing.Hat.Trail
>    Tracing.Hat.SExp
>    Tracing.Hat.HighlightStyle

It would be nice to indicate in some way "this exports some gunk that
happened to be useful", and "this exports a nice clean API that I
expect to be used" - although I guess that can go in the
documentation.

I still think its nice to have a some sort of classification as to
what libaries are "general Haskell libraries" and which are "Hat
Tracing stuff" - for example Tracing.Hat.HighlightStyle isn't really
anything to do with Hat or Tracing.

However, what you propose is close enough that I'm not overly fussed
and would happily accept it.

Thanks

Neil