fun sum [ ] = 0
  | sum (h::t) = h + (sum t);

fun length [ ] = 0
  | length (h::t) = 1 + (length t);

##</code><code>##

multi sub sum ()          returns Int { 0             }
multi sub sum (*$x, *@xs) returns Int { $x + sum(@xs) }

multi sub length ()          returns Int { 0               }
multi sub length (*$x, *@xs) returns Int { 1 + length(@xs) }

##</code><code>##

sub sum {
    return 0 unless @_;
    my ($h, @t) = @_;
    return $h + sum(@t);
}

sub length {
    return 0 unless @_;
    shift;
    return 1 + length(@_);
}