Simple Backtracking Control Verbs

• (*FAIL)

• • simplest verb. Syntactic sugar for (?!)
  • can be used to force the engine to backtrack and therefore find all matches in a pattern, similar to how “exhaustive matching” would work in Perl6
  • • 'aaab' =~ /a+b?(?{print $&})(*FAIL)/
  • would print out every possible substring that matches the pattern /a+b?/