simple_function_composition.exs

defmodule SimpleFC do
  require Integer

  def even(n), do: Integer.is_even(n)
  def negate(n), do: not n

  def compose(func1, func2) do
    fn (n) ->
      func2.(func1.(n))
    end
  end

  def not_even(n) do
    compose(&even/1, &negate/1).(n)
  end
end