Process

• create a file named hollow_diamond.ex
• write the code

pyramid = fn number ->
  for i <- 1..number do
    # for printing spaces

    spaces =
      for j when j <= number - i <- 1..number do
        " "
      end

    # for printing star
    star_number = 2 * i - 1

    star =
      for k <- 0..star_number do
        if k == 0 || k == 2 * i - 2 do
          "*"
        else
          " "
        end
      end

    spaces ++ star
  end
end

reverse_pyramid = fn number ->
  for i <- 1..number do
    # for printing spaces

    spaces =
      for j when j < i <- 0..i do
        " "
      end

    # for printing star
    start_number = (number - i) * 2 - 1

    star =
      for k when k >= 1 <- 0..start_number do
        if k == 1 || k == start_number do
          "*"
        else
          " "
        end
      end

    spaces ++ star
  end
end

hollow_diamond = fn number ->
  diamond = pyramid.(number) ++ reverse_pyramid.(number)

  diamond
  |> Enum.into("", fn string ->
    string = Enum.join(string)
    "#{string}\n"
  end)
end

IO.puts(hollow_diamond.(10))
IO.puts(hollow_diamond.(5))

• run elixir hollow_diamond.ex

Result

         *
        * *
       *   *
      *     *
     *       *
    *         *
   *           *
  *             *
 *               *
*                 *
 *               *
  *             *
   *           *
    *         *
     *       *
      *     *
       *   *
        * *
         *


    *
   * *
  *   *
 *     *
*       *
 *     *
  *   *
   * *
    *

Happy Coding!