Two possible approaches to coercion in set comparisons

leaning on MMD

multi sub infix:<<(<)>>(Bag $a, Bag $b --> Bool) {
    [&&] $a.keys.map({ $a{$_} < $b{$_} });
}

multi sub infix:<<(<)>>(Bag $a, Any $b --> Bool) {
    $b = $b.bag(:view);
    [&&] $a.keys.map({ $a{$_} < $b{$_} });
}

multi sub infix:<<(<)>>(Any $a, Bag $b --> Bool) {
    $a = $a.bag(:view);
    [&&] $a.keys.map({ $a{$_} < $b{$_} });
}

using junctions and given-when

only sub infix:<<(<=)>>(Any $a, Any $b --> Bool) {
    my ($c,$d);
    given $a|$b {
        when Mix     { $c = $a.Mix(:view); $d = $b.Mix(:view); }
        when Bag     { $c = $a.Bag(:view); $d = $b.Bag(:view); }
        default      { $c = $a.Set(:view); $d = $b.Set(:view); }
    }
    [&&] $c.keys.map({ $c{$_} <= $d{$_} });
}