Hi there,
I've been writing an evaluator for a toy Smalltalk-like language, and reading the paper "The Evolution of Smalltalk" by Dan Ingalls which discusses the history from ST-72 to Squeak to get a better understanding of how STs worked under the hood.
My understanding from this paper (mainly, pages 4-6) and others is that in early implementations, objects were responsible for the evaluation of their own messages in a fairly low level sense
That is, ST-72 programs were first parsed in a sort of pre-processing step -- in such a way where objects could be initialized and differentiated from the tokens representing their messages. Then the messages as raw token streams were parsed into ASTs by the objects themselves, which then interpreted them. Is this actually how it worked?
It makes sense to me that it would work in this way -- I was thinking when writing a parser for my toy Smalltalk that the parser should probably be fairly ignorant about the nature of the messages it parses, outside of being able to distinguish selectors and arguments, and binary messages vs keyword vs unary messages.
In particular it probably does not know anything about precedence rules, since that would violate encapsulation and modularity -- e.g. in 3 + 2*4, it should be whatever method is invoked by the + selector that determines what happens to the tokens 2*3 rather than the parser -- i.e. whether we add 2 first and then multiply the sum by 3, or perform the multiplication and then add the product as in standard arithmetic.
But it also seems like this would force developers to mix tedious parsing code with domain code, which feels kind of messy. I would really appreciate any clarification on this -- apologies if this is the wrong list for this sort of question, I'm very new to the community
Thank you