Maybe

gistfile1.ex

defmodule Foo do
  use Pipe

  def maybe({:ok, val}, f), do: f.(val)
  def maybe({:bad, _} = lhs, f), do: lhs
  def maybe(_, _), do: raise ArgumentError

  def dec(num) do
    if num > 0 do
      {:ok, num-1}
    else
      {:bad, num}
    end
  end

  def main() do
    res = pipe_with &maybe/2,
    {:ok, 3} |> dec |> dec |> dec |> dec |> dec
    IO.puts(inspect(res))
  end
end