#!/usr/bin/perl -w
use strict;
use Devel::Peek qw(mstat);

my $testn = shift || 50;

my $result = factorial_iterative($testn);
print "goto factorial_iterative($testn) returns $result\n";

my ($product, $counter, $max_count);

sub factorial_iterative {
  my $n = shift;
  ($product, $counter, $max_count) = (1, 1, $n);

  return fi_helper();
}

sub fi_helper {
  my $j;
  if ($counter > $max_count) {
    mstat "return product";
    return $product;
  } else {
    ($product, $counter, $max_count) =
        ($counter * $product, $counter + 1, $max_count);
    goto &fi_helper;
  }
}