Re: One type for all

[Tucker Taft <stt@averstar.com>]

Robert Dewar wrote:
> ...
> So thanks, it is indeed the case that Pascal does NOT have
> structural type equivalence, which is what I remembered (any
> other conclusion would have been a big surprise!)

I suspect the confusion comes from the early Pascal reports (e.g. <= 2nd ed.),
which were in fact ambiguous on the issue of type equivalence,
leading some implementations to choose name equivalence, and
others to choose structural equivalence.  For structured assignment,
it required the types to be "identical" but it didn't define
that in any rigorous way.  The ISO standard opted for name 
equivalence, but by that time, there were already
implementations using structural equivalence.  The initial ISO
standard was weak enough that it might not have been sufficient
to get all implementors to follow the official rules.

-- 
-Tucker Taft   stt@averstar.com   http://www.averstar.com/~stt/
Technical Director, Distributed IT Solutions  (www.averstar.com/tools)
AverStar (formerly Intermetrics, Inc.)   Burlington, MA  USA