our $USE_A_FUZZY = '(?(?{!$fuzzies--})(?=A)(?=Z))';

{
   my $string = 'apple';
   my $max_fuzzies = 2;

   my $re = '^';
   $re .= sprintf("(?:%s|${USE_A_FUZZY}.)", quotemeta($1))
      while ($string =~ /(.)/g);
   $re .= "\$";

   $re = do { use re 'eval'; qr/$re/ };

   our $fuzzies;
   local $fuzzies;

   while (<DATA>) {
      chomp;
      $fuzzies = $max_fuzzies;
      if (/$re/) {
         $fuzzies = $max_fuzzies - $fuzzies;
         if ($fuzzies) {
            print("Fuzzy match with $_ ($fuzzies fuzzies).$/");
         } else {
            print("Exact match with $_.$/");
         }
      } else {
         print("No match with $_.$/");
      }
   }
}