Ruby array partition

partition.rb

def partition(arr, int)
  list = [[],[]]
  return list if arr.empty?

  if int == 0
    list[1] = arr
    return list
  end

  if int.negative?
    left = arr.length - int.abs
    left = 0 if left.negative?
    right = int.abs
  else
    right = arr.length - int
    right = 0 if right.negative?
    left = int
  end

  list[0] = arr.first(left)
  list[1] = arr.last(right)
  list
end