Alternate Version of #to_range

to_range.rb

class Array
  def to_range
    self.sort!
    highs = self.select { |x| !self.include?(x+1) } 
    lows = self.select  { |x| !self.include?(x-1) } 
    lows.zip(highs).map { |a,b| a..b } 
  end
end

Sort the array at the beginning and there's no need to sort when selecting highs and lows.

We can't do that, as it has an after-effect in that the original array is altered. So if I do this:

array = [3, 2, 1]
array.to_range
array # will equal [1, 2, 3]

If we were going to alter the original and follow standard Ruby conventions, we'd have to put an exclamation point at the end of the method name to signify that it alters the original.