Experimenting with cumulative probability

probability.exs

trials = 10_000

simulation =
  4
  |> Stream.iterate(fn dollars ->
    case :rand.uniform(4) do
      1 -> dollars - 1
      2 -> dollars + 1
      _n -> dollars
    end
  end)
  |> Stream.with_index()
  |> Stream.map(fn
    {-1, i} -> i
    state -> state
  end)

Stream.repeatedly(fn -> Enum.find(simulation, &is_integer/1) end)
|> Stream.take(trials)
|> Enum.sum()
|> then(&(&1 / trials))
|> IO.inspect()