function_composition.exs

defmodule PipeFunctionComposition do
  require Integer

  def even(n), do: Integer.is_even(n)
  def negate(n), do: not n
  def multiply_by(n, factor), do: n * factor
  
  @doc """
  true if the passed number is not even
  """
  def not_even(n) do
    n
    |> even 
    |> negate
  end
  
  @doc """
  true if the given number, multiplied by a factor, is even
  """
  def is_even_multiplied_by(n, factor) do
    n 
    |> multiply_by(factor) 
    |> even
  end
end