xo

A Tic-tac-toe library for Elm.

An example

It shows how to use the library to play Tic-tac-toe.

import XO exposing (Player(..))

game0 = XO.start X
-- Playing { board = [], first = X, turn = X }

game1 = XO.play (1,1) game0 |> Result.withDefault game0
-- Playing { board = [((1,1),X)], first = X, turn = O }

game2 = XO.play (0,0) game1 |> Result.withDefault game1
-- Playing { board = [((0,0),O),((1,1),X)], first = X, turn = X }

XO.play (3,3) game2
-- Err (OutOfBounds (3,3))

XO.play (1,1) game2
-- Err (Occupied (1,1))

game3 = XO.play (2,2) game2 |> Result.withDefault game2
-- Playing { board = [((2,2),X),((0,0),O),((1,1),X)], first = X, turn = O }

game4 = XO.play (2,1) game3 |> Result.withDefault game3
-- Playing { board = [((2,1),O),((2,2),X),((0,0),O),((1,1),X)], first = X, turn = X }

XO.toString game4
-- "o...x..ox"
--
-- Which represents the following board:
--
--    0   1   2
-- 0  o |   |
--   ---+---+---
-- 1    | x |
--   ---+---+---
-- 2    | o | x
--

-- Where should I play?
XO.findGoodPositions game4
-- Ok { optimum = W, possibilities = [((0,2),3),((1,2),3)] }
--
-- i.e. X can win in 3 moves if X is played at (0,2) or (1,2)

game5 = XO.play (1,2) game4 |> Result.withDefault game4
-- Playing { board = [((1,2),X),((2,1),O),((2,2),X),((0,0),O),((1,1),X)], first = X, turn = O }

-- It doesn't matter where you play now, you're going to lose
game6 = XO.play (0,2) game5 |> Result.withDefault game5
-- Playing { board = [((0,2),O),((1,2),X),((2,1),O),((2,2),X),((0,0),O),((1,1),X)], first = X, turn = X }

-- Make the winning play
game7 = XO.play (1,0) game6 |> Result.withDefault game6
-- GameOver { board = [((1,0),X),((0,2),O),((1,2),X),((2,1),O),((2,2),X),((0,0),O),((1,1),X)], first = X, outcome = Win X [R2], turn = X }

XO.toState game7
-- { first = X, outcome = Win X [((1,0),(1,1),(1,2))], turn = X }

Public API

A high-level overview of the types and functions that make up the library.

Player, nextPlayer

Game, start

Position, PlayError, play

Rules, defaultRules, playAgain

State, Outcome, Line, toState

openPositions

Tile, map

toString

Report, Optimum, AnalysisError, findGoodPositions