Array#sorted? method for discovering whether an array is sorted in any order. Optionally takes a block and yields to it each element to discover the sort value for that element.

array_sorted.rb

class Array
  def sorted?(&block)
    case length
    when 0, 1 then true
    else
      init_signum = nil
      if block
        init_signum = block.call(self[0]) <=> (prev = block.call(self[1]))
      else
        init_signum = self[0] <=> (prev = self[1])
      end
      for i in 2...self.length
        elt = self[i]
        elt = block.call(elt) if block

        if (prev <=> elt) != init_signum
          return false
        end
        prev = elt
      end
      return true
    end
  end

  def sortage(&block)
    if block
      values = self.map(&block)
    else
      values = self.dup
    end
    prev = values.shift
    values.map {|elt| res = prev <=> elt; prev = elt ; res}
  end

end

I guess the #sortage method should go on some other module and not clutter up Array's public methods.