defmodule Random do
  def init() do
    :random.seed(:erlang.now())
  end
  def normal(mean, sd) do
    {a, b} = {:random.uniform(), :random.uniform()}
    mean + sd * (:math.sqrt(-2 * :math.log(a)) * :math.cos(2 * :math.pi * b))
  end
end

Random.init()
xs = for _ <- 1..1000, do: Random.normal(1.0, 0.5)