match within action method?

gistfile1.txt

#! /usr/bin/env perl6

grammar G {
    rule TOP { <hi>+ %% <.line-end> }
    token hi { hi }
    token line-end { \n }
}

class A {
    method TOP ($/) {
        my $res = $<hi>.join(' ');

        # Cannot assign to a readonly variable ($/) or a value
        if $res.match(/ "hi hi" /) {
            note "HI HI";
        }
    }
}

G.parse("hi\nhi\r\nhi\rhi\r\n", :actions(A.new));