ruby--ruby/benchmark/other-lang/tak.pl

sub tak {
    local($x, $y, $z) = @_;
    if (!($y < $x)) {
	return $z;
    } else {
	return &tak(&tak($x - 1, $y, $z),
		    &tak($y - 1, $z, $x),
		    &tak($z - 1, $x, $y));
    }
}
&tak(18, 9, 0);