Plain-text CLI table renderer for Elixir

defmodule CliTable do
  def render(headers, rows) do
    widths = widths([headers | rows])
    sep = Enum.map_join(widths, "+", &String.duplicate("-", &1 + 2))
    [format_row(headers, widths), sep | Enum.map(rows, &format_row(&1, widths))]
    |> Enum.join("\n")
  end

  defp widths(rows) do
    rows
    |> Enum.zip()
    |> Enum.map(fn col -> col |> Tuple.to_list() |> Enum.map(&String.length/1) |> Enum.max() end)
  end

  defp format_row(row, widths) do
    cells = row |> Enum.zip(widths) |> Enum.map(fn {cell, w} -> String.pad_trailing(cell, w) end)
    "| " <> Enum.join(cells, " | ") <> " |"
  end
end