Lisp has strong typing, so 1 is 1, not "1" or #\1, which, unless mark has a built in way of annotating types doesn't give this any advantages over s-expressions.
Lisp expressions also don't have any annoying type clutter that you have to have at every node in the syntax. Like (1 "1") is just a list of two things; we don't need the word "list" anywhere.
