Raku (Perl 6)

I'm doing different language each day, all solutions here.

Today's Raku: src

I really wanted to try Raku's Grammar feature for this. Took ages till it worked and anyone even remotely familiar with the language will probably scoff the following, but I tend to like it:

grammar Monkey {
    token TOP       { <monkey><items><operation><test><iftrue><iffalse> }
    token monkey    { 'Monkey ' <num> ':'\n }
    token items     { '  Starting items: ' [<num> ', '?]+\n }
    token operation { '  Operation: new = old ' <op>' '[<num> | 'old']\n }
    token test      { '  Test: divisible by ' <num>\n }
    token iftrue    { '    If true: throw to monkey ' <num>\n }
    token iffalse   { '    If false: throw to monkey ' <num> }
    token num       { \d+ }
    token op        { ['*' | '+'] }
}