Elixir format difference in strings

difference_between_strings.ex

  @doc """
  Truncates the middle of a string

  iex> Utils.String.truncate_middle("some really long string that needs truncating", 10)
  "some..ting"

  iex> Utils.String.truncate_middle("some really long string that needs truncating", 100)
  "some really long string that needs truncating"
  """
  def truncate_middle(str, count) when is_binary(str) and is_integer(count) do
    if String.length(str) < count do
      str
    else
      edges = Integer.floor_div(count, 2) - 2
      front = String.slice(str, 0..edges)
      back = String.slice(str, -(edges + 1)..-1)
      "#{front}..#{back}"
    end
  end

  @doc """
  Formats the difference between to strings for output

  iex> Utils.String.format_diff("zip growth", "zip books")
  "\e[39mzip \e[31mgr\e[32mb\e[39mo\e[31mwth\e[32moks"
  """
  def format_diff(string1, string2) do
    String.myers_difference(string1, string2)
    |> Enum.reduce([], fn
      {:eq, str}, acc -> [IO.ANSI.default_color() <> Utils.String.truncate_middle(str, 50) | acc]
      {:del, str}, acc -> [IO.ANSI.red() <> str | acc]
      {:ins, str}, acc -> [IO.ANSI.green() <> str | acc]
    end)
    |> Enum.reverse()
    |> Enum.join("")
  end

example.md

This helper prints a pretty diff between two strings: