Raku and the Knapsack

Question

The following is a solution to the knapsack problem and supposed to be my entry to this weeks perl challenge. I wonder if this is a good use of dynamic variables or is it too confusing?

I use them so I don't have to put the variables $n, @things and @result in all the signatures of the multi-subs and carry them through the recursion.

sub MAIN()
{
 my @data =
 { thing => 'R', weight => 1, amount => 1 },
 { thing => 'B', weight => 1, amount => 2 },
 { thing => 'G', weight => 2, amount => 2 },
 { thing => 'Y', weight => 12, amount => 4 },
 { thing => 'P', weight => 4, amount => 10 }
 ;
 my ( $v, $w, @t ) = knapsack( 15, 5, @data );
 say "Value: $v, Weight: $w";
 say "Taken: ", join ",", @t.map: *<thing>;
}
multi sub knapsack( Int $total-weight, Int $*n, @*things )
{
 my @*results;
 my Int $optimal-value = my Int $current-value = knapsack( $total-weight, 0 );
 my Int $optimal-weight = my Int $current-weight = @*results[0].pairs.first({ .value eqv $optimal-value }).key // -1;
 return $optimal-value, $optimal-weight, |gather
 {
 # walk the results and find the good ones
 for ^$*n -> $i
 {
 my %d = @*things[ $i ];
 my $next-weight = $current-weight - %d<weight>;
 my $next-value = @*results[ $i + 1; $next-weight ];
 with $next-value
 {
 if $next-weight >= 0 && $next-value == $current-value - %d<amount>
 {
 take @*things[ $i ];
 $current-value -= %d<amount>;
 $current-weight -= %d<weight>;
 }
 }
 }
 take @*things[ $*n - 1 ]
 if $current-value > 0;
 };
}
multi sub knapsack( Int $weight, Int $i where @*results[ $i ; $weight ].defined ) { @*results[ $i ; $weight ] }
multi sub knapsack( Int $weight, Int $i where $i >= $*n ) { 0 }
multi sub knapsack( Int $weight, Int $i where $i < $*n )
{
 my $leftover-weight = $weight - @*things[ $i ]<weight>;
 my $current-value = knapsack( $weight, $i + 1 );
 my $next-value = $leftover-weight >= 0
 ?? ( @*things[ $i ]<amount> + knapsack( $leftover-weight, $i + 1 ) )
 !! 0;
 @*results[ $i ; $weight ] = ( $current-value, $next-value ).max
}