Thanks for sharing – took a quick crack at porting the first game Acey Ducey.

Acey Ducey

This is a simulation of the Acey Ducey card game.

In the game, the dealer (the computer) deals two cards face up. You have an option to bet or not to bet depending on whether or not you feel the next card dealt will have a value between the first two.

Your initial money is set to $100; you may want to alter this value if you want to start with more or less than $100. The game keeps going on until you lose all your money or interrupt the program.

The original program author was Bill Palmby of Prairie View, Illinois.

defmodule Game do
  @deck for suit <- [:spades, :hearts, :clubs, :diamonds], value <- 1..13, do: {suit, value}

  defstruct funds: 100, deck: []

  def play(), do: play(%__MODULE__{}) # for convenience

  def play(%__MODULE__{funds: funds}) when funds <= 0, do: IO.puts("~~~ game over ~~~")
  def play(%__MODULE__{deck: deck} = game) when length(deck) < 3, do: play(%{game | deck: Enum.shuffle(@deck)})
  def play(%__MODULE__{deck: deck, funds: funds} = game) do
    IO.gets("<hit enter>\n")

    [first_card, second_card, third_card | remaining_deck] = deck

    IO.puts("~~~ new round ~~~")
    IO.puts("first card: #{format(first_card)}")
    IO.puts("second card: #{format(second_card)}\n")
    IO.puts("funds: $#{funds}")

    bet = prompt_to_place_bet(funds)
    new_funds = if win?(first_card, second_card, third_card), do: funds + bet, else: funds - bet

    IO.puts("\nthird card: #{format(third_card)}")
    IO.puts("funds: $#{funds} => $#{new_funds}")
    IO.puts("~~~ end round ~~~\n")

    play(%{game | deck: remaining_deck, funds: new_funds})
  end

  # re-prompt if invalid integer and/or out of bounds
  defp prompt_to_place_bet(funds) do
    input = IO.gets("place your bet: $")
    case Integer.parse(input) do
      {bet, _} when bet in 0..funds -> bet
      _ -> prompt_to_place_bet(funds)
    end
  end

  # for a stricter win condition (non-inclusive)
  defp win?({_, first}, {_, second}, {_, third}) when third > first and third < second, do: true
  # for a looser win condition (inclusive)
  #defp win?({_, first}, {_, second}, {_, third}) when third in first..second, do: true
  defp win?(_, _, _), do: false

  defp format({suit, value}) do
    case value do
      1 -> "ace of #{suit}"
      11 -> "prince of #{suit}"
      12 -> "queen of #{suit}"
      13 -> "king of #{suit}"
      value -> "#{value} of #{suit}"
    end
  end
end

Game.play() # equivalent to Game.play(%Game{funds: 100, deck: 100})

For transparency and posterity’s sake, there’s a bug in win?/3. (╯°□°）╯︵ ┻━┻

The version above depends on the unfortunate and incorrect assumption that the first card’s value is less than that of the second card. The version below uses Enum.sort/1 to not rely on that assumption being true.

  # for a stricter win condition (non-inclusive)
  defp win?({_, first}, {_, second}, {_, third}) do
    [floor, ceiling] = Enum.sort([first, second])
    (floor < third) && (third < ceiling)
  end
  # for a looser win condition (inclusive)
  #defp win?({_, first}, {_, second}, {_, third}) do
    #[_, middle, _] = Enum.sort([first, second, third])
    #middle == third
  #end