Euchre
Image source: By — atchius (msg) - Scanned (self-made), Public Domain
Summary
Euchre is a trick-taking game for four players in partnerships. A shortened deck of 24 cards is shuffled and 5 cards are dealt to each player. The top card of the remaining deck is turned face-up. Players in turn decide if the suit displayed will be the trump suit. If no player is willing make it trump, any suit can then be declared trump. Players can also decide to play alone (their partner would sit out) in the hopes of earning more points. The other Jack of the same color as the trump suit becomes trump, and the two Jacks are the highest ranks of trump. Players play 5 tricks, rotating the lead to the player who won the last trick. The team that wins the majority of tricks earns points.
Rules of Play
These rules are summarized from https://www.pagat.com/euchre/euchre.html.
Variants Used
The North American variant is used, so there is no Joker card. Only the player that chooses the trump suit is allowed to “go alone” and play without a partner. When all players initially pass on using face-up card, and the first three players pass on making a trump suit, we use the “stick the dealer” variant to force the dealer to choose a trump suit.
Related Games
Euchre defines its own genre of trick-taking games. Other games in this genre include Five Hundred and Charlemagne.
Information Flow
The diagram above visualizes information flow in Euchre using a single random rollout in CardStock. Visibility is attached to card locations, so all cards in a location share the same visibility; information is revealed or concealed as cards move between locations and ownership changes.
Public locations are shown in green, hidden locations in yellow, private locations in blue, and memory locations in light gray. Locations containing cards with distinct backs are indicated with bold borders. Rectangles denote ownership (players or table), and directed edges show card movement between locations and resulting visibility changes. Taken information is shown with red dotted edges (public to private/hidden), and shared information with blue dashed edges (private cards transferred to another player).
RECYCLE Code
The rules for Euchre are coded in RECYCLE, a card game description language, to encourage standardized implementations across different systems.
You can also Download the code.
;; Euchre (American Rules)
;; https://www.pagat.com/euchre/euchre.html
(game
(setup
;; Set up the players, 2 teams of 2 players, alternating
(create players 4)
(create teams (1, 3) (2, 4))
;; Create the deck source
(create deck (game iloc STOCK)
(deck (RANK (NINE, TEN, J, Q, K, A))
(COLOR (RED (SUIT (HEARTS, DIAMONDS)))
(BLACK (SUIT (CLUBS, SPADES)))))))
;; Prepare for the game
(do (
(shuffle (game iloc STOCK))
(all player 'P
(repeat 5 (move (top (game iloc STOCK))
(top ('P iloc HAND)))))
(move (top (game iloc STOCK))
(top (game vloc TURNED)))
(set (game str LEADSUIT) NONE)
(set (game str TRUMPSUIT) (cardatt SUIT (top (game vloc TURNED))))
(set (game str TRUMPCOLOR) (cardatt COLOR (top (game vloc TURNED))))))
;; First chance for bidding
(stage player
(end (or (all player 'P (== ('P str BID) PASS))
(any team 'T (== ('T str BID) MAKER))))
(choice (
(set ((current player) str BID) PASS)
(do (
(set ((current player) str BID) PICKUP)
(set ((team (current player)) str BID) MAKER)
(set ((team (next player)) str BID) DEFENDER)))
(do (
(set ((current player) str BID) ALONE)
(set ((team (current player)) str BID) MAKER)
(set ((team (next player)) str BID) DEFENDER))))))
;; if someone said PICKUP or ALONE, then the dealer takes the card
;; all pass bids are wiped
(do (
((any team 'T (== ('T str BID) MAKER))
(move (top (game vloc TURNED))
(top ((previous player) iloc HAND))))
(all player 'P
((== ('P str BID) PASS)
(set ('P str BID) NONE)))))
;; if PICKUP or ALONE, Dealer swaps out trump card for one of their own
(stage player
(end (all player 'P (== (size ('P iloc HAND)) 5)))
(choice (
((== (size ((current player) iloc HAND)) 6)
(any ((current player) iloc HAND) 'C
(move 'C (top (game iloc STOCK)))))
((== (size ((current player) iloc HAND)) 5)
(turn pass)))))
;; If no one picked up earlier,
;; now the players get to pick the suit, not the one shown earlier
;; dealer is forced to make a bid (Stick the Dealer rules)
(stage player
(end (any team 'T (== ('T str BID) MAKER)))
(choice (
((any (other player) 'OP (!= ('OP str BID) PASS))
(set ((current player) str BID) PASS))
((!= HEARTS (game str TRUMPSUIT))
(do (
(set ((current player) str BID) ALONE)
(set ((team (current player)) str BID) MAKER)
(set ((team (next player)) str BID) DEFENDER)
(set (game str TRUMPSUIT) HEARTS)
(set (game str TRUMPCOLOR) RED))))
((!= DIAMONDS (game str TRUMPSUIT))
(do (
(set ((current player) str BID) ALONE)
(set ((team (current player)) str BID) MAKER)
(set ((team (next player)) str BID) DEFENDER)
(set (game str TRUMPSUIT) DIAMONDS)
(set (game str TRUMPCOLOR) RED))))
((!= SPADES (game str TRUMPSUIT))
(do (
(set ((current player) str BID) ALONE)
(set ((team (current player)) str BID) MAKER)
(set ((team (next player)) str BID) DEFENDER)
(set (game str TRUMPSUIT) SPADES)
(set (game str TRUMPCOLOR) BLACK))))
((!= CLUBS (game str TRUMPSUIT))
(do (
(set ((current player) str BID) ALONE)
(set ((team (current player)) str BID) MAKER)
(set ((team (next player)) str BID) DEFENDER)
(set (game str TRUMPSUIT) CLUBS)
(set (game str TRUMPCOLOR) BLACK))))
((!= HEARTS (game str TRUMPSUIT))
(do (
(set ((team (current player)) str BID) MAKER)
(set ((team (next player)) str BID) DEFENDER)
(set (game str TRUMPSUIT) HEARTS)
(set (game str TRUMPCOLOR) RED))))
((!= DIAMONDS (game str TRUMPSUIT))
(do (
(set ((team (current player)) str BID) MAKER)
(set ((team (next player)) str BID) DEFENDER)
(set (game str TRUMPSUIT) DIAMONDS)
(set (game str TRUMPCOLOR) RED))))
((!= SPADES (game str TRUMPSUIT))
(do (
(set ((team (current player)) str BID) MAKER)
(set ((team (next player)) str BID) DEFENDER)
(set (game str TRUMPSUIT) SPADES)
(set (game str TRUMPCOLOR) BLACK))))
((!= CLUBS (game str TRUMPSUIT))
(do (
(set ((team (current player)) str BID) MAKER)
(set ((team (next player)) str BID) DEFENDER)
(set (game str TRUMPSUIT) CLUBS)
(set (game str TRUMPCOLOR) BLACK)))))))
;; if partner going alone, then discard all of your cards
(stage team
(end (all player 'P (== ('P str READY) TRUE)))
(do (
(all (current team) 'TP
(do (
(set ('TP str READY) TRUE)
((and (any (current team) 'CT (== ('CT str BID) ALONE))
(!= ('TP str BID) ALONE))
(do (
(set ('TP str BID) DUMMY)
(repeat all (move (top ('TP iloc HAND))
(top ('TP iloc ALONE)))))))))))))
;; players play a round 5 times
(stage player
(end (all player 'P (== (size ('P iloc HAND)) 0)))
;; players play a hand once
(stage player (end (all player 'P (or (> (size ('P vloc TRICK)) 0)
(== ('P str BID) DUMMY))))
(choice (
;; if dummy player (partner going alone) then pass)
((== ((current player) str BID) DUMMY)
(turn pass))
;; if first player, play any card, remember it in the lead spot
((== (game str LEADSUIT) NONE)
(any ((current player) iloc HAND) 'C
(do (
((or (!= (cardatt RANK 'C) J)
(and (== (cardatt RANK 'C) J)
(!= (cardatt COLOR 'C) (game str TRUMPCOLOR))))
(set (game str LEADSUIT) (cardatt SUIT 'C)))
((and (== (cardatt RANK 'C) J)
(== (cardatt COLOR 'C) (game str TRUMPCOLOR)))
(set (game str LEADSUIT) (game str TRUMPSUIT)))
(move 'C (top ((current player) vloc TRICK)))))))
;; if following player and cannot follow SUIT
;; play any card
((and (!= (game str LEADSUIT) NONE)
(== (size (filter ((current player) iloc HAND) 'L
(or (and (== (cardatt RANK 'L) J)
(== (cardatt COLOR 'L) (game str TRUMPCOLOR))
(== (game str LEADSUIT) (game str TRUMPSUIT)))
(and (== (cardatt RANK 'L) J)
(!= (cardatt COLOR 'L) (game str TRUMPCOLOR))
(== (cardatt SUIT 'L) (game str LEADSUIT)))
(and (!= (cardatt RANK 'L) J)
(== (cardatt SUIT 'L) (game str LEADSUIT)))))) 0))
(any ((current player) iloc HAND) 'C
(move 'C (top ((current player) vloc TRICK)))))
;; if following player and can follow SUIT
;; play any card that follows SUIT
((!= (game str LEADSUIT) NONE)
(any (filter ((current player) iloc HAND) 'L
(or (and (== (cardatt RANK 'L) J)
(== (cardatt COLOR 'L) (game str TRUMPCOLOR))
(== (game str LEADSUIT) (game str TRUMPSUIT)))
(and (== (cardatt RANK 'L) J)
(!= (cardatt COLOR 'L) (game str TRUMPCOLOR))
(== (cardatt SUIT 'L) (game str LEADSUIT)))
(and (!= (cardatt RANK 'L) J)
(== (cardatt SUIT 'L) (game str LEADSUIT))))) 'C
(move 'C (top ((current player) vloc TRICK))))))))
;; after players play hand, computer wraps up trick
(do (
;; solidfy card recedence
(set (game points PRECEDENCE)
(((SUIT : (game str TRUMPSUIT)) 200)
((RANK : J) (SUIT : (game str TRUMPSUIT)) 1)
((RANK : J) (COLOR : (game str TRUMPCOLOR)) 304)
((SUIT : (game str LEADSUIT)) 100)
((RANK : A) 14) ((RANK : K) 13) ((RANK : Q) 12)
((RANK : J) 11) ((RANK : TEN) 10) ((RANK : NINE) 9)))
;; determine who won the hand, set them first next time, and give them a point
(set (game str LEADSUIT) NONE)
(cycle next (owner (max (union (all player 'P ('P vloc TRICK)))
using (game points PRECEDENCE))))
(inc ((next player) sto TRICKSWON))
;; discard all the played cards
(all player 'P
((> (size ('P vloc TRICK)) 0)
(move (top ('P vloc TRICK))
(top (game vloc DISCARD))))))))
;; determine team score
(stage team
(end (all player 'P (== ('P sto TRICKSWON) 0)))
(do (
(set ((current team) sto TRICKSWON) 0)
(all (current team) 'TP
(do (
(inc ((current team) sto TRICKSWON) ('TP sto TRICKSWON))
(set ('TP sto TRICKSWON) 0))))
;; team made their cumulative bid, score positive points
((and (>= ((current team) sto TRICKSWON) 3)
(== ((current team) str BID) MAKER))
(inc ((current team) sto SCORE)))
;; bonus for all five tricks
((and (== ((current team) sto TRICKSWON) 5)
(== ((current team) str BID) MAKER))
(inc ((current team) sto SCORE)))
;; bonus for going alone and getting all five tricks
((and (== ((current team) str BID) MAKER)
(== ((current team) sto SCORE) 2)
(any (current team) 'TP (== ('TP str BID) ALONE)))
(inc ((current team) sto SCORE) 2))
;; points for defenders if successful Euchre
((and (>= ((current team) sto TRICKSWON) 3)
(== ((current team) str BID) DEFENDER))
(inc ((current team) sto SCORE) 2)))))
(scoring max ((team (current player)) sto SCORE)))