Flaws like this arise from trying to be too clever with syntax. Function application with parentheses, literal regular expressions without clear delimiters, etc. Syntax should be describable in a handful of universal rules. Lisp is the extreme in this regard, the rule is simply: parentheses nest properly. But you can build surprisingly rich syntax with a simple set of rules so long as you lay out those rules first and conform the syntax to them as you go.
