I have just recently finished a 'ChessBoard' module that is meant to
represent a chess board. I could use some opinions and/or suggestions
on the module.
To give an example of how this can be used right now, and was my
immediate goal, you can do this:
*ChessBoard> putStr $ cout defaultBoard
+----+----+----+----+----+----+----+----+
| RB | NB | BB | QB | KB | BB | NB | RB |
+----+----+----+----+----+----+----+----+
| PB | PB | PB | PB | PB | PB | PB | PB |
+----+----+----+----+----+----+----+----+
| | | | | | | | |
+----+----+----+----+----+----+----+----+
| | | | | | | | |
+----+----+----+----+----+----+----+----+
| | | | | | | | |
+----+----+----+----+----+----+----+----+
| | | | | | | | |
+----+----+----+----+----+----+----+----+
| PW | PW | PW | PW | PW | PW | PW | PW |
+----+----+----+----+----+----+----+----+
| RW | NW | BW | QW | KW | BW | NW | RW |
+----+----+----+----+----+----+----+----+
I have not determined exactly how I will be making moves, but the
logic will not be in my program. I am going to be using a chess engine
in another process (I haven't chosen a chess engine yet that works on
both windows and mac through stdin/stdout).
The module itself follows, I appreciate any thoughts you might have.
module ChessBoard where
import Data.Sequence
import Data.Foldable
import Data.Maybe
import Data.List as List
class NiceLook a where
cout :: a -> String
data Piece = Bishop | Rook | Knight | King | Queen | Pawn | NoPiece
deriving (Show, Eq)
instance NiceLook Piece where
cout Bishop = "B"
cout Rook = "R"
cout Knight = "N"
cout Queen = "Q"
cout Pawn = "P"
cout King = "K"
cout _ = " "
data Colour = Black | White | NoColour
deriving (Show, Eq)
instance NiceLook Colour where
cout Black = "B"
cout White = "W"
cout NoColour = " "
-- error "..." might be useful
data Square = Square Piece Colour
deriving (Show, Eq)
instance NiceLook (Square) where
cout (Square p c) = (cout p) ++ (cout c)
data Row = Row (Seq Square)
deriving (Show, Eq)
instance NiceLook (Row) where
cout (Row s) = "|" ++ foldMap (\x -> " " ++ cout x ++ " |")
s -- thnx Saizan
makeRow n = case (List.length n) of
8 -> Row (fromList n)
_ -> error "Row is not 8 squares"
makeColouredSquares n c = makeRow $ map makeSquare (zip n (replicate 8
c))
makeSquare (n,c) = Square n c
pawns = [Pawn, Pawn, Pawn, Pawn, Pawn, Pawn, Pawn, Pawn]
back = [Rook, Knight, Bishop, Queen, King, Bishop, Knight, Rook]
blank = [NoPiece, NoPiece, NoPiece, NoPiece, NoPiece, NoPiece,
NoPiece, NoPiece]
data Board = Board (Seq Row)
deriving (Show, Eq)
instance NiceLook (Board) where
cout (Board c) = borderOutput ++ "\n" ++ (foldMap (\x -> cout x +
+ "\n" ++ borderOutput ++ "\n") c)
defaultBoard = Board (makeColouredSquares back Black <|
makeColouredSquares pawns Black <|
makeColouredSquares blank NoColour <|
makeColouredSquares blank NoColour <|
makeColouredSquares blank NoColour <|
makeColouredSquares blank NoColour <|
makeColouredSquares pawns White <|
makeColouredSquares back White <| empty)
borderOutput = "+" ++ (List.foldr1 (++) $ replicate 8 "----+")
