PhillyDev Slack #daily_programmer for March 1, 2017

alpha_bet.ex

defmodule AplhaBet do
  @moduledoc """
  The word `chimps` is an example of a word that's in alphabetical order. Write
    a program that prints out if the word is in alphabetical order. For bonus
    make it test backwards too!
  """

  @doc """
  Returns true if the given string is in alphabetical or reverse-alphabetical
    order

  # Examples
      iex> AplhaBet.alphabetical?("chimps")
      true
      iex> AplhaBet.alphabetical?("spoonfeed")
      true
      iex> AplhaBet.alphabetical?("asked")
      false
  """
  @spec alphabetical?(String.t) :: boolean
  def alphabetical?(word) do
    ordered_chars = sorted_characters(word)

    ordered_chars
    |> Enum.join
    |> Kernel.==(word)

    or

    ordered_chars
    |> Enum.reverse
    |> Enum.join
    |> Kernel.==(word)
  end

  @spec sorted_characters(String.t) :: list(String.t)
  defp sorted_characters(word) do
    word
    |> String.graphemes
    |> Enum.sort
  end
end