/* 
  carddeck returns a deck of cards in normal order, represented as a list of
  tuples, each tuple representing the card value and suit.
*/

carddeck(CardDeck) :- addcard(1, spade, CardDeck).

/*
  addcard takes the number and suit of the current card to be added, and 
  returns the new set of cards with the current card added
*/

addcard(1, nil, []).	/* terminate when all suits exhausted */

addcard(1, Suit, CardDeck) :-
  addcard(2, Suit, CardDeck1),
  append([card(ace, Suit)], CardDeck1, CardDeck).

addcard(Number, Suit, CardDeck) :-
  Number > 1, Number < 11,
  Number1 is Number + 1,
  addcard(Number1, Suit, CardDeck1),
  append([card(Number, Suit)], CardDeck1, CardDeck).

addcard(11, Suit, CardDeck) :-
  nextsuit(Suit, NextSuit),
  addcard(1, NextSuit, CardDeck1),
  append([card(jack, Suit), card(queen, Suit), card(king, Suit)], CardDeck1, 
    CardDeck).

/*
  nextsuit moves to the next suit.
*/

nextsuit(spade, heart).
nextsuit(heart, diamond).
nextsuit(diamond, club).
nextsuit(club, nil).

/*
  standard append
*/

append([], Ys, Ys).
append([X | Xs], Ys, [X | Zs]) :- append(Xs, Ys, Zs).