My point was that "Code editing is tree editing" sounds a bit like if you can understand the syntax tree, you understand what the code does – which isn't true h

My point was that "Code editing is tree editing" sounds a bit like if you can understand the syntax tree, you understand what the code does – which isn't true here. Trees don't show the recursion[1], and a tree-view of code (with e.g. folding) might even give a false impression that what's inside one branch is somehow self-contained. Ie. Turing Machines are more expressive than CFG's :-) Not that tree-view's aren't helpful (indentation is important, and editing Lisp with paredit is a real joy), but there's much more to code-editing than tree-manipulation. [1] Unless your "tree"-view is actually a lazy call-graph …