joker

Poker library in Go: hand evaluation, No-Limit Hold'em, sit-and-gos, and a browser cash table.

Requires Go 1.26.

go get github.com/notnil/joker@master

Packages

Package	Role
pkg/hand	Cards, decks, and 5–7 card hand ranking
pkg/holdem	No-Limit Hold'em table, pots, and legal actions
pkg/bot	Heuristic players (Nit, Calling Station, LAG)
pkg/play	9-max cash session: one human seat vs bots
pkg/tournament	Single-table SNGs and ICM equity
pkg/jokertest	Fixed decks for tests

Hands

package main

import (
	"fmt"

	"github.com/notnil/joker/pkg/hand"
	"github.com/notnil/joker/pkg/jokertest"
)

func main() {
	cards := jokertest.Cards("Ks", "Qs", "Js", "As", "9d")
	h := hand.New(cards)
	fmt.Println(h)            // high card ace high
	fmt.Println(h.Ranking())  // HighCard
}

hand.New selects the best five-card poker hand from the cards you pass (high or low, with optional config for games that ignore flushes or straights).

No-Limit Hold'em

package main

import (
	"log"
	"math/rand"

	"github.com/notnil/joker/pkg/hand"
	"github.com/notnil/joker/pkg/holdem"
)

func main() {
	tbl, err := holdem.NewTable(holdem.Config{
		Seats:  6,
		Stakes: holdem.Stakes{SmallBlind: 50, BigBlind: 100},
	}, hand.NewDealer(rand.New(rand.NewSource(1))))
	if err != nil {
		log.Fatal(err)
	}
	_ = tbl.Sit(0, "Alice", 10000)
	_ = tbl.Sit(1, "Bob", 10000)

	h, err := tbl.StartHand()
	if err != nil {
		log.Fatal(err)
	}
	if err := h.Act(holdem.FoldAction()); err != nil {
		log.Fatal(err)
	}
	if h.Done() {
		_ = tbl.ApplyResults(h)
	}
}

Hand.LegalActions() lists what the player to act may do. Raises are raise-to (total chips in for the street). Hand.View(hero) is a JSON snapshot that hides other players' hole cards until showdown.

Cash table in the browser

A 9-max cash game (50/100, 10k stacks) against eight bots:

make -C cmd/wasm
go run ./cmd/server

Open http://localhost:8080. HTML and CSS pick up on refresh; after rebuilding WASM, hard-refresh the page.

pkg/play.NewCash is the same session without a browser.

Tournaments

tournament.NewSNG runs a single-table sit-and-go with a blind schedule and payouts. tournament.ICM(stacks, payouts) returns Malmuth–Harville chip equities as integers that sum to the prize pool.

Tests

go test ./...