stuff.pl6

use nqp;

my %type-map = ('QAST::IVal' => 'I', 'QAST::Var' => 'V', 'QAST::Op' => 'O', 'QAST::Stmts' => 'S');

my $prog = 'my $aa = 4; say "([$aa]" ~ (3 + $aa);';
my @hl = ' ' xx $prog.chars;

sub traverse($indent, Mu $item) {
    if $item.^name eq "QAST::SVal" {
        say ("  " x $indent) ~ $item.^name ~ " '" ~ $item.value ~ "' ";
    }
    elsif nqp::can($item, "dump_annotations") {
        say ("  " x $indent) ~ $item.^name ~ " " ~ $item.dump_annotations;
    }
    else {
        say ("  " x $indent) ~ $item.^name;
    }
    if nqp::can($item, "node") {
        if $item.node.^name eq "Perl6::Grammar" {
            say ("  " x $indent) ~ "# " ~ $item.node.from ~ "-" ~ $item.node.to;
            for $item.node.from..$item.node.pos-1 -> $i {
                @hl[$i] = %type-map{$item.^name} // '?';
            }
        }
    }
    if $item.^name eq "Str" {
        say ("  " x $indent) ~ "'" ~ $item ~ "'";
        return;
    }
    if nqp::can($item, "list") {
        for @($item.list) -> $c {
            traverse($indent + 1, $c);
        }
    }
}

my $item = nqp::getcomp('perl6').compile($prog, compunit_ok => 1, target => 'ast');
traverse(0, $item);

say $prog;
say @hl.join;
say "";