M-expressions did fail. Their greatest failure is that they persist as a universal strawman that's useful for killing any conversation about evolving lisp's syn

M-expressions did fail. Their greatest failure is that they persist as a universal strawman that's useful for killing any conversation about evolving lisp's syntax. M-expressions didn't just fail because they were unnecessary; they also failed because they just weren't a very good syntax. They were more cluttered and less readable than S-expressions, while adding no real practical value. But Clojure has arguably demonstrated that you can evolve on Lisp syntax without going to M-expressions, or even changing S-expressions all that much, just by adding a few new bits of literal syntax and sprinkling some clever macros into the standard library. (A macro invocation may not technically be syntax from the parser's perspective, but it sure feels like syntactic sugar from a user experience perspective.) And, while I haven't actually tried them at all, I've at least been intrigued by t-expressions. They seem to achieve some nice things like git-friendliness and easier visual scannability without sacrificing on macro-ability.