An elixir module for defining power function without using multiplication operator.

two_power_eight_quiz.ex

defmodule Compute do 

	def twoPlus(num), do: 2+num

	def twoTimes(0), do: 0

	def twoTimes(num) when num < 0, do: -twoTimes(-num) 

	def twoTimes(num) when num > 0, do: twoPlus(twoTimes(num-1))

	def twoPower(0), do: 1

	def twoPower(num) when num > 0, do: twoTimes(twoPower(num-1))

	def twoPower(num) when num < 0, do: "1/#{twoPower(-num)}" #I just print the rational number style string :D
end


IO.puts Compute.twoPlus(3) #=> 5
IO.puts Compute.twoTimes(-4) #=> -8
IO.puts Compute.twoTimes(4) #=> 8
IO.puts Compute.twoPower(-8) #=> 1/256
IO.puts Compute.twoPower(8) #=> 256