Find bare lang tags

The only tricky thing here is the use of the ms form of match, short for m:sigspace. This causes whitespace in the regex to be considered "significant", that is, it matches optional whitespace at those positions, as if you'd put \s* there. Of course, the regexes themselves are in Raku syntax, which is quite different from Perl 5 regex syntax (and arguably much cleaner). Regex syntax is perhaps the area in which Raku diverges most from Perl 5.

my $lang = '(no language)';
my $total = 0;
my %blanks;

for lines() {
  when / '<lang>' / {
    %blanks{$lang}++;
    $total++;
  }
  when ms/ '==' '{{' 'header' '|' ( <-[}]>+? ) '}}' '==' / {
    $lang = $0.lc;
  }
}

say "$total bare language tag{ 's' if $total != 1 }\n";
say .value, ' in ', .key for %blanks.sort;

Output:

2 bare language tags

1 in (no language)
1 in perl