But I'll add one delightful trait: sexps split usually complex parsing stage in two simple separate ones:
- chars -> sexp
- sexp -> meaning (special forms / anticipated mental evaluation).
At least not with plain text. There's some terrfic research in composing languages - currently the best is Tratt and Diekmann's Language Boxes, which enable arbitrary syntax composition by means of the programmer specifying the syntax boundaries explicitly - which requires a more sophisticated editor than out plain text notepad variants.
With language boxes, and their prototype editor Eco, in the end, they're ultimately storing a tree of data in their own custom format - it doesn't matter what encoding is used, just as it doesn't matter whether lisp uses parens, braces or whitespace - what really matters is that you encode things deterministically into trees which can be easily reasoned about without requiring some "magic" (AI) which attempts to create a tree from a sequence of characters unambiguously, when the programmer knows and can specify exactly what he means.
Ah, and I just realized, it wasn't Parr, but Tratt that wrote the paper "Parsing: The Solved Problem That Isn't".