PhillyDev Slack #DailyProgrammer March 16, 2017

sorter.ex

defmodule Sorter do
  @doc """
  Takes a list and prints the list with the non zero index position before it was sorted.

  ## Example
      iex> Sorter.sortit([34, 7, 38, 1])
      "1 was in position 3"
      "7 was in position 1"
      "34 was in position 0"
      "38 was in position 2"
      :ok
  """
  @spec sortit(list(pos_integer)) :: list(String.t)
  def sortit(values) do
    values
    |> Enum.with_index
    |> Enum.map(fn({value, key}) -> {value, "#{value} was in position #{key + 1}"} end)
    |> Enum.sort_by(fn({value, _}) -> value end)
    |> Enum.each(fn({_, message}) -> IO.inspect message end)
  end
end


defmodule FasterSorter do
  @doc """
  Takes a list and prints the list with the non zero index position before it was sorted.
  ## Example
      iex> Sorter.sortit([34, 7, 38, 1])
      "1 was in position 3"
      "7 was in position 1"
      "34 was in position 0"
      "38 was in position 2"
      :ok
  """
  @spec sortit(list(pos_integer)) :: list(String.t)
  def sortit(values, position \\ 1) do
    values
    |> sortit(%{}, 1)
    |> Enum.each(fn({_, value}) -> IO.inspect(value) end)
  end

  def sortit([], acc, _), do: acc
  def sortit([head|tail], acc, position) do
    sortit(
      tail,
      Map.put(acc, head, "#{head} was in position #{position}"),
      position + 1
    )
  end
end