Tim Rowledge <tim at sumeru.stanford.edu> wrote:

	What? You mean that you have to do special work to be able to push
	objects? Ludicrous! How could anybody live such a dumb restricion. Why,
	that would be as dumb as integers and floats not being proper objects!
	
Remember, this is talking about Simula >>67<<.  It was developed before
"modals" were invented for Algol 68 (yes, I know they aren't in Algol 68,
but they were invented _for_ Algol 68 and described in the Algol Bulletin).
Hindley-Milner type checking and Eiffel were as yet undreamed of.

If you're going to develop a type-safe single-inheritance OO language
starting from an Algol 60 base and have never seen parametric polymorphism,
you are going to end up with something very like Simula, complete with
the restriction that objects can only go into a scheduling set (a real
example from Simula 67) if they belong to a class that was declared to
inherit from the appropriate scheduling set element class.

Smalltalk's main improvements to Simula 67 amount to removing things.
(Including restrictions.)