I can't remember anything in that direction from Scheme. In the original Scheme papers there was an exploration of the Actor ideas of message passing. But gene

I can't remember anything in that direction from Scheme. In the original Scheme papers there was an exploration of the Actor ideas of message passing. 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...