remcopeereboom

def color(a, i)
  a[i]
end

def swap(a, i, j)
  a[i], a[j] = a[j], a[i]
end

def flag_sort(a)
  # Indices (not colors):

remcopeereboom

class Promise < BasicObject
  def initialize(&computation)
    @computation = computation
  end

  def __result__
    if @computation
      @result = @computation.call
      @computation = nil # So we don't redo the calculation next time.
    end

remcopeereboom

class EvenStream
  attr_reader :value

  def initialize(n = 0)
    @value = n
    @next = lambda { EvenStream.new(n + 2) }
  end

  def next
    @next.call

remcopeereboom

require_relative 'tail_call_optimization' # All files loaded AFTER this file with have tail-recursion enabled.
require_relative 'tail_factorial'