This is good point. Thanks. It seems that the original view of John John McCarthy - before the decade of different implementations, was "right",

> It is nothing Scheme has contributed.

Scheme, it seems, re-emphasized it, much later, as the answer to the mess made by different implementations.

I could give you an example form a complete different field, in order to show how common such pattern is.

The very first Aryan Vedas emphasize the notion of taking inspirations from the nature and remaining in unity with it. They use deities as symbols for the major natural powers and appreciate them.

Then these ideas has been taken by "other people" and mechanistic, ritual-based religions, based on worshiping and praising of anthropomorphic idols emerge. This, in turn, resulted in emergence of Upanishads as thinking people got sick with all that nonsense, and from the Upanishads the Advaita Vedanta and Buddhism schools has been developed (and got ruined by "commentators").

This is a social pattern. I can't tell how meany times in history these cycles of inflation and reduction, mass hysteria and returning back to the very few "great insights" happened.

I am not telling you that this my analogy for the evolution of Lisps is precise - only the MIT guys behind Scheme could tell whether I am wrong or not - but I have this notion, based on what I read in books and watched in lectures, so I, if you have no objections, would still hold my opinions.

But generic operations were explored in detail in actor implementations in Lisp and in various forms of object systems in Lisp. Scheme itself as a language only provided hard-coded generic functions. The 1985 Scheme report included nothing generic beyond the few hard-defined generic functions. At a time when software in Lisp explored already user defined multiple inheritance, message sending, pattern-based invocation, ... Sussman himself knew Maclisp very well. True, SICP showed how to implement and use generic operations, but then that was already a decade old...