#!/usr/bin/perl -w
use strict;
use warnings;

use Benchmark qw(timethese cmpthese);

sub add_rec {
        my ($first, @rest) = @_;


        if (!defined $first) {
                0;
        }
        else {
                die "operand may not be negative!" unless $first >= 0;
                if ($first == 0) {
                        add_rec(@rest);
                }
                else {
                        1 + add_rec($first-1, @rest);
                }
        }
}

sub add_iter {
        my $accumulator = 0;
        for my $op (@_) {
                for my $i (1 .. $op) {
                        $accumulator = $accumulator+1;
                }
        }
        $accumulator;
}

cmpthese(100000, {
        'Recursive' => sub { 2 == add_rec(2,2); },
        'Iterative' => sub { 2 == add_iter(2,2); }
});