Conway's Game of life

game_of_life.rb

require 'set'

cells = lambda do |world, (x, y)|
  [
    [-1,-1], [0, -1], [1, -1],
    [-1, 0],          [1,  0],
    [-1, 1], [0,  1], [1,  1],
  ].map do |(dx, dy)|
    [x+dx, y+dy]
  end.partition { |_cell| world.include?(_cell) }
end

advance = lambda do |world|
  Set.new.tap do |_world|
    world.each do |cell|
      occupied, available = cells[world, cell]

      _world << cell if (2..3).include?(occupied.size)

      available.each do |cell|
        occupied, _ = cells[world, cell]
        _world << cell if occupied.size == 3
      end
    end
  end
end

b = Set.new
b << [0,0]
b << [1,0]
b << [2,0]
b << [0,1]
b << [1,2]

100.times do 
  b = advance[b]
end

p b

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