Conway's Game Of Life

game_of_life.rb

class GameOfLife
  attr_reader :height, :width

  def initialize
    @board  = {
      [10,10] => true,
      [10,11] => true,
      [10,12] => true,
    }
    @height = 40
    @width  = 100
    @generation = 0
  end

  def loop
    sleep 0.5
    @board = next_generation
    print_board
    puts "Generation: #{@generation}"
    @generation += 1
    loop
  end

  private

  def next_generation
    next_board = {}
    height.times do |y|
      width.times do |x|
        alive = @board[[x,y]]
        neighbour_count = live_neighbours(x, y)
        if (alive && (neighbour_count == 2 || neighbour_count == 3)) || (!alive && neighbour_count == 3)
          next_board[[x,y]] = true
        end
      end
    end
    next_board
  end

  def live_neighbours(x, y)
    [
      @board[[x+1,y+1]],
      @board[[x+1,y]],
      @board[[x+1,y-1]],
      @board[[x,y+1]],
      @board[[x,y-1]],
      @board[[x-1,y+1]],
      @board[[x-1,y]],
      @board[[x-1,y-1]],
    ].compact.count
  end

  def print_board
    system("clear")
    height.times do |y|
      width.times do |x|
        cell = @board.has_key?([x,y]) ? "#" : " "
        print cell
      end
      print "\n"
    end
  end
end

GameOfLife.new.loop
# copy and paste into a file
# then run in terminal `$ ruby filename.rb`