ChessLogic

Description

This package contains logic to play the game of chess. Functional Chess validator written in Elixir.

It includes fcardinaux/chessfold source files, as hex does not permit non hex dependencies.

It uses leex to parse pgn files, and chessfold to implement chess logic. Both in Erlang.

It understands following rules:

• draw by 3 times the same position
• draw by 50 moves rule
• mat
• pat
• check
• taken
• en passant
• castling

But it does not understand draw by not enough material rule! It is not meant to be an AI of some sort, just a simple chess move validator (and generator), to be used in a larger project.

It also supports importing/exporting pgn files.

Installation

The package can be installed by adding chess_logic to your list of dependencies in mix.exs:

def deps do
  [{:chess_logic, "~> 0.1.0"}]
end

Available in Hex.

Documentation can be found at https://hexdocs.pm/chess_logic.

Erlang and dialyxir configuration

Because of some warnings detected in Erlang outside code (chessfold, leex), it is nice to configure dialyxir to avoid them…

Update mix.exs

  erlc_paths: ["src"],
  dialyzer: [
    ignore_warnings: "dialyzer.ignore-warnings"
  ],

Add file ./dialyzer.ignore-warnings

Unknown function chessfold
Guard test RowId::0
The variable _ can never match since previous clauses completely covered the type
Function yyrev/2 will never be called

Sample usage

More sample usage in the test folder.

iex(1)> g = ChessLogic.Game.new
%ChessLogic.Game{
  current_position: %ChessLogic.Position{
    fen: "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1",
    position: [
      ["r", "n", "b", "q", "k", "b", "n", "r"],
      ["p", "p", "p", "p", "p", "p", "p", "p"],
      [" ", " ", " ", " ", " ", " ", " ", " "],
      [" ", " ", " ", " ", " ", " ", " ", " "],
      [" ", " ", " ", " ", " ", " ", " ", " "],
      [" ", " ", " ", " ", " ", " ", " ", " "],
      ["P", "P", "P", "P", "P", "P", "P", "P"],
      ["R", "N", "B", "Q", "K", "B", "N", "R"]
    ]
  },
  history: [],
  result: nil,
  status: :started,
  winner: nil
}
iex(2)> {:ok, g} = ChessLogic.Game.play(g, "e2e4")
{:ok,
 %ChessLogic.Game{
   current_position: %ChessLogic.Position{
     fen: "rnbqkbnr/pppppppp/8/8/4P3/8/PPPP1PPP/RNBQKBNR b KQkq e3 0 1",
     position: [
       ["r", "n", "b", "q", "k", "b", "n", "r"],
       ["p", "p", "p", "p", "p", "p", "p", "p"],
       [" ", " ", " ", " ", " ", " ", " ", " "],
       [" ", " ", " ", " ", " ", " ", " ", " "], 
       [" ", " ", " ", " ", "P", " ", " ", " "],
       [" ", " ", " ", " ", " ", " ", " ", " "],
       ["P", "P", "P", "P", " ", "P", "P", "P"],
       ["R", "N", "B", "Q", "K", "B", "N", "R"]
     ]
   },
   history: [
     %{
       fen: "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1",
       move: "e2e4",
       san: "e4"
     }
   ],
   result: nil,
   status: :playing,
   winner: nil
 }}
iex(3)> {:ok, g} = ChessLogic.Game.play(g, "g8f6")
{:ok,
 %ChessLogic.Game{
   current_position: %ChessLogic.Position{
     fen: "rnbqkb1r/pppppppp/5n2/8/4P3/8/PPPP1PPP/RNBQKBNR w KQkq - 1 2",
     position: [
       ["r", "n", "b", "q", "k", "b", " ", "r"],
       ["p", "p", "p", "p", "p", "p", "p", "p"],
       [" ", " ", " ", " ", " ", "n", " ", " "],
       [" ", " ", " ", " ", " ", " ", " ", " "],
       [" ", " ", " ", " ", "P", " ", " ", " "],
       [" ", " ", " ", " ", " ", " ", " ", " "],
       ["P", "P", "P", "P", " ", "P", "P", "P"],
       ["R", "N", "B", "Q", "K", "B", "N", "R"]
     ]
   },
   history: [
     %{
       fen: "rnbqkbnr/pppppppp/8/8/4P3/8/PPPP1PPP/RNBQKBNR b KQkq e3 0 1",
       move: "g8f6",
       san: "Nf6"
     },
     %{
       fen: "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1",
       move: "e2e4",
       san: "e4"
     }
   ],
   result: nil,
   status: :playing,
   winner: nil
 }}
iex(4)> g |> ChessLogic.Game.to_pgn()
"1. e4 Nf6"