There is this totally normal mix Elixir project/repository (code and tests and stuff - just a library for now, no Phoenix or anything).
Then added a LiveBook notebook at notebooks/dicect.livemd - needed some exploratory data visualization.

When this code is executed from the inside the LiveBook:

data = [
  %{"category" => "A", "score" => 28},
  %{"category" => "B", "score" => 55}
]

Vl.new()
|> Vl.data_from_values(data)

It returns:

** (Protocol.UndefinedError) protocol Enumerable not implemented for %Table.Mapper{enumerable: [%{"category" => "A", "score" => 28}, %{"category" => "B", "score" => 55}], fun: #Function<1.129280379/1 in Table.Mapper.map/2>} of type Table.Mapper (a struct). This protocol is implemented for the following type(s): Date.Range, File.Stream, Function, GenEvent.Stream, HashDict, HashSet, IO.Stream, Jason.OrderedObject, List, Map, MapSet, Range, Stream
    (elixir 1.17.2) lib/enum.ex:1: Enumerable.impl_for!/1
    (elixir 1.17.2) lib/enum.ex:166: Enumerable.reduce/3
    (elixir 1.17.2) lib/enum.ex:4423: Enum.map/2
    (vega_lite 0.1.10) lib/vega_lite.ex:304: VegaLite.data_from_values/3
    #cell:r6qixazynpxprvhi:9: (file)

But, when it is run from the iex -S mix prompt, it returns a VegaLite data structure.

What is missing?

The setup part of the LiveBook:

Mix.install(
  [
    {:dicect, path: Path.join(__DIR__, ".."), env: :dev}
  ],
  config_path: :dicect,
  lockfile: :dicect
)

Current dependencies in mix.exs are:

  ...
  defp deps do
    [
      {:dialyxir, "~> 1.4", only: [:dev, :test], runtime: false},
      {:credo, "~> 1.7", only: [:dev, :test], runtime: false},
      {:logger_json, "~> 6.1"},
      {:vega_lite, "~> 0.1.10"},
      {:kino, "~> 0.14.1"},
      {:tucan, "~> 0.3.0"},
      {:kino_vega_lite, "~> 0.1.8"}
    ]
  end
  ...

1. Also tried tucan , had a similar story - since it uses VegaLite I guess.