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Re: Clause 10, Expression Evaluation
Thorsten Siebenborn <7_born@xxxxxx> wrote:
FORTH and all other stack-based languages (most Virtual Machines are
stack-based, too) have a strict and rigid rule of expression evaluation:
the stack order.
So these languages can be debugged exactly the way they run in
full-speed mode: You CAN crash-test a certain kind of VOLVO to
verify that the PORSCHE from the same firm run faultless.
You can run them in a debugger; there are even omnisicient debuggers
in Java or OCaml where you can move forward and backward in time from
a breakpoint and inspect the values. Claiming that such an ability
isn't useful....words are failing me.
It isn't useful to rely on such a property in a standard like IEEE
754R.
Yes, there are such languages. However, the vast majority of
relevant languages are not like that, and most of the most important
are so fundamentally different that such a property cannot be added
to them. I need just include C, C++ and Fortran to justify the
latter.
Furthermore, there are no parallel languages based on Hoare's
seminal structure that have such a property and, as I have said
several times, there cannot be any general ones with it. It would
be possible to have a restricted parallel language (perhaps even
one based on BSP), but no more and not OpenMP or POSIX threads.
Claiming that an IEEE 754R specification that makes sense in the
context of Forth, Java and BSP but not C, C++, Fortran, OpenMP and
POSIX threads is useful....words are failing me.
Regards,
Nick Maclaren,
University of Cambridge Computing Service,
New Museums Site, Pembroke Street, Cambridge CB2 3QH, England.
Email: nmm1@xxxxxxxxx
Tel.: +44 1223 334761 Fax: +44 1223 334679