flatten_everything.rb

module Enumerable
  def method_missing(meth, *args, &block)
    if "#{meth}" =~ /flat_(.*)/
      send($1, *args, &block).flatten
    else
      super
    end
  end

  def respond_to_missing?(meth, include_private = false)
    "#{meth}".start_with?("flat_") || super
  end
end

p [[1,2,3], [1,2,3]].flat_zip([[4,5,6], [4,5,6]])
p [[1,2,3], [1,2,3]].flat_flat_flat_map { |x| x * 2 }
p [1,2,3].flat_zip([2,4,6])
p [1,2,3, 4].flat_partition(&:even?)

__END__
[1, 2, 3, 4, 5, 6, 1, 2, 3, 4, 5, 6]
[1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3]
[1, 2, 2, 4, 3, 6]
[2, 4, 1, 3]