Conway's Game of Life

gol.rb

seed = [[0,0],[0,1],[0,2]]
puts "First generation:"
puts seed.to_s

# Point surrounding a given point
perimeter = ->(x, y){
    [
      [x - 1, y + 1], [x, y + 1], [x + 1, y + 1],
      [x - 1, y    ],             [x + 1, y    ],
      [x - 1, y - 1], [x, y - 1], [x + 1, y - 1]
    ]
  }

# All points and their perimeters
world = ->(seed){
    seed.inject([]) do |array, point|
      array.concat(perimeter.(*point))
    end.concat(seed).uniq
  }

# For a dead point and a living perimeter, get the next state
dead_next_point = ->(point, living){
    if living.size == 3
      point
    end
  }

# For a point and living seed, get the living points in the perimeter
living_perimeter = ->(point, seed){
    seed & perimeter.(*point)
  }

# For a point and living perimeter, get the next state
living_next_point = ->(point, living){
    case living.size
      when 0, 1 then nil
      when 2, 3 then point
      else
        nil
    end
  }

# For a point and living seed, get the next state
next_point = ->(point, seed){
    if seed.include?(point)
      living_next_point.(point, living_perimeter.(point, seed))
    else
      dead_next_point.(point, living_perimeter.(point, seed))
    end
  }

# Gather each points' next state
generate = ->(seed){
  world.(seed).map do |point|
    next_point.(point, seed)
  end.compact
}

puts "More generations"
9.times do |num|
  seed = generate.(seed)
  puts seed.to_s
end