One man’s data is another man’s
procedure; Simula can model or automate an interpretation. That makes it
a programming language as well as a modeling language.
Project Logos, (“logical operating
system”) was a demonstration of the < control graph / data graph >
approach to proof of correctness for an operating system. It was also a
modeling language with two aspects. In this case, those aspects were
control and data because that is consistent with how the principal investigator
and staff interpreted the world around them – control v data. At
the time (1970’s), the computing view of the world was divided by the
control versus data viewpoint.
Simula was designed around the same
Later, the object oriented, event based
programming style was advanced and accepted, and the whole control/data divide
went away as such a dominant approach to large system software development.
Again, there is a subjective matter of
interpretation, based on past individual successes and failures of similar actions
in the same class, how to classify and organize actions and their detritus into
coherent and mostly consistent world views. Mostly just the starting
point mythology is different from one person to the next.
Rich AT EnglishLogicKernel DOT com
9 4 9 \ 5 2 5 - 5 7 1 2
On Behalf Of Jack Ring
Sent: Wednesday, December 15, 2010
Subject: Re: [ontolog-forum] FW:
(Moved from ontology-summit)
--- orignal post by John Sowa ---
Perhaps I am being too picky but I think Simula is
a modeling language, not a programming language.
The borderline is not sharp. You can take a declarative language
like Horn-clause logic or data flow diagrams, design a compiler
or interpreter for it, and you have a programming language.
But Simula 67 was definitely designed and used as a programming
language. The primary reason why it didn't become popular is that
Oslo University, where it was designed and
implemented, tried to
recoup their investment by selling it.
I was at IBM at the time (1969), and I wanted to get a copy to try
it out. But the cost (in 1969 dollars) was $20K for commercial
companies. My manager said that if it was necessary for my job,
we could buy it. But I had to admit that my major interest was
to try it out and "kick the tires".
A few years later, Niklaus Wirth designed and implemented
a much simpler language called Pascal. Instead of selling it,
he gave the compiler away to anybody that asked for it. Most
universities were looking for a successor to Algol 60, and
Algol 68 was too complex. So they got a copy of the Pascal
compiler and ported it to their favorite hardware.
I was in GE Aerospace an 1969. Dr. Shuey, GE R&D Center, brought it
to my attention and suggested I try it for representing a descriptive model of
a spacecraft then for formulating a prescriptive model. I guess we misused it
but it sure gave us insight into ways of representing systems. Then we wrote
the programs in Jules Own Version of the International Algorithmic Language
because the USAF said we had to.