Robert Cringely and Dave Winer talk about the Lispic origins of Dave's outlining software:

Bob: How did the Outliner come about?

Dave: Well, I was talking with a friend of mine who was a Lisp programmer, really loved Lisp, and he was telling me about a feature that they had in Lisp editors called Function Illusion, which allowed you to - you know, Lisp was all about names with parentheses. So it's just a ton of - so in order to manage all those parentheses, the software that you use to edit a Lisp program knows how to take all the detail out and just show you the sort of skeleton of it. So you can sort of walk through the structure of a Lisp program.

And I thought, since I wasn't programming in Lisp, I was programming in Pascal and then C, that it would be nice to have something like that for those languages. And so I decided to write an editor like that. This is when I was at Wisconsin. And I showed it to my colleagues in the Computer Science Department. And this is an experience that I repeat to this day - that you try to - computer guys don't wanna try new things out. I mean the theory is that we're very innovative people. But, in fact, we're anything but innovative. And so I showed it to them. They scratched their heads, and they said, “Well, that looks great, but I think I'll continue using the regular old editor that I'm using.”

And I thought it would be like in Kurt Vonnegut's Cat's Cradle Ice Nine that just sorta, you know, the whole world froze because of this great thing. Well, not quite - nobody wanted to use it. So it sorta sat around...

I have no idea what is meant by the term “function illusion”, but maybe he's talking about structure editors. Or emacs-style folding. Damn computer scientists.