[MLton] possible change to annotations

[Stephen Weeks]

> That raises the question of whether or not opening an MBasis (as
> with a .mlb or basis id reference) also adds the annotations into
> scope.  The current implementation does not.

I think that makes sense, and jibes with the fact that the annotion
environment always starts out with a clean slate when evaluating an
mlb.

> > The current syntax is a special case
> >
> >   ann "..." in <bdec> end
> >   ===> local ann "..." in <bdec> end
> 
> As noted above, forceUsed and ffiStr would probably be different in this
> regard.

This is a problem.  The following won't work.

  ann "forceUsed" in <bdec> end
  ===> <bdec> ann "forceUsed"

One could try

  ann "forceUsed" in <bdec> end
  ===> local in <bdec> ann "forceUsed" end

But I don't see a good way to come up with a semantics for "the
current local basis".

A good argument to leave well enough alone.