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


##</code><code>##

 my $life = new life : 20;


##</code><code>##

 loop { $life.display() }


##</code><code>##

 class life
 {

##</code><code>##

  has Int          $.count;
  has Int          $.dimension;
  has Array of Bit @.grid;


##</code><code>##

  method BUILD(Int $dimension)
  {
    $.count = 0;
    $.max = $dimension - 1;

##</code><code>##

    my Array of Bit @.grid is dim($dimension,$dimension)
                           is default(0);


##</code><code>##

    @grid[$dimension / 2 - 1][$dimension / 2] = 1;
    @grid[$dimension / 2 - 1][$dimension / 2 + 1] = 1;
    @grid[$dimension / 2][$dimension / 2] = 1;
    @grid[$dimension / 2][$dimension / 2 - 1] = 1;
    @grid[$dimension / 2 + 1][$dimension / 2] = 1;

##</code><code>##

    @.grid = @grid;
  }


##</code><code>##

  sub iterate (&block)
  {

##</code><code>##

    for 0..$.max -> $x
    {
      for 0..$.max -> $y
      {
        block($x,$y);
      }
    }
  }


##</code><code>##

  method calculate() is private
  {
    my @newgrid;
    iterate
    {

##</code><code>##

      my $live = sum(@.grid[$^x-1..$^x+1][$^y-1..$^y+1]);
      @newgrid[$^x][$^y] =  $live==2 && @.grid[$^x][$^y]
                         || $live==3;
    }
    @.grid = @newgrid;
  }

  method display
  {
    iterate {
      print $.grid[$^x][$^y] ?? '+' :: '.';
      print "\n" if $^x == $.max;
    }
    print "\n";

##</code><code>##

    print "Turn $(++$.count), press enter to continue or ctl-c to quit;

##</code><code>##

    <$*IN>;

##</code><code>##

   .calculate();
  }
}