easily inspecting a thing that is being piped through functions in Elixir

pipe_inspect.ex

defmodule PipeInspect do
  #
  # Usage:
  #
  # Instead of temporarily breaking up a series of pipes to inspect the values:
  # ```
  # partial_result =
  #   1..100_000
  #   |> Enum.map(&(&1 * 3))
  #
  # IO.inspect partial_result
  #
  # partial_result
  # |> Enum.filter(odd?)
  # |> Enum.sum
  # ```
  #
  # We can just inline an inspector that plays well with our pipe.
  # We can even include a message to be printed with it.
  #
  # ```
  # 1..100_000
  # |> Enum.map(&(&1 * 3))
  # |> pi()
  # |> Enum.filter(odd?)
  # |> pi("just the odd ones")
  # |> Enum.sum
  # ```
  #
  def pi(thing) do
    IO.inspect thing
    thing
  end
  def pi(thing, msg) do
    IO.puts msg
    pi(thing)
  end
end