I guess I wasn't clear, sorry. What Alan Kay meant by the "spreadsheet value rule" and what the phrase "a limited form of first-order functional progamming" means are semantically equivalent; they are the same thing.
I have no idea if Alan Kay ever used the latter phrase, but it was easier to use that phrase here on HN than Alan Kay's made up phrase, which would have be difficult to understand without the content of the article explaining it.
Ah, gotcha. I agree with you that spreadsheet formulas are a limited form of first-order functional programming. But the memory model with which they are coupled is just as important (I have in mind the grid addressing system and dataflow semantics) and this does not fit as nicely into the FP paradigm. But I'm repeating what I said in other comments.
But the memory model with which they are coupled is just as important (I have in mind the grid addressing system and dataflow semantics)
Totally agree. My startup is using hierarchical grids as our core datatypes for just that reason (we also support Function cells that are used as values).
"Naming" is one of the core problems in computer science, and grids/spreadsheets elegantly solve that problem for many ad hoc use cases, where functional programming (in all its forms) does not.