It's my understanding that Perl 6's syntax mutation capabilities will be a good deal safer than using C
s. In fact, I'd argue that the current state of the Perl syntax munging art, Source Filters, are more like C macros than Perl 6 rules will be. Perl 6 rules are so much safer, they take away the need to do your own (possibly fallible) parsing of Perl source code, you just modify the rules at the appropriate level in the grammar and away you go. Also, rule based syntax modification is lexically scoped, which is definitely handy...