> [example] is not possible, because the names for type t in M1 and M2,
 > and the module names for module Std clash...
 >
 > The only solution that seems to make sense and does not impose
 > excessive work on the user is, IMHO, to provide for a facility to
 > rename types and modules...

Kathleen Fisher and Paul Govereau and I have been working out a
detailed proposal, but operating primarily on signatures, not
structures:

  http://www.eecs.harvard.edu/~nr/pubs/els-abstract.html

In some cases (such as renaming to avoid collisions), these operations
extend nicely to the structure level.  But in others, particularly
meet and join, extension to structures is not obvious.  

We would certainly be very interested in hearing from Caml programmers
whether you think our proposed extensions meet your needs.


Norman

P.S. We've made no effort to avoid introducing new syntax---at the
present stage, we are most interested in coming up with a good design
for ML-like module systems.  Figuring out how to fit the design into
an existing language with minimal disruption is a separate question.