A petty irritant for me is the official sanction of square brackets: they are ugly and unhelpful in reading code. They create a very discordant visual rhythm and should be summarily outlawed. Square brackets are a gross violation of the LISP Party Ethic and offending implementers shall be required to submit thorough self-criticism of their motivations and then will be summarily shot. I really mean this. Square brackets are not defined in R7RS lexical syntax.