chess.hs

import Data.Array

data Piece = 
  Pawn | Rook | Knight | Bishop | Queen | King | Empty
  deriving Show

type Board = [[Piece]]

emptyRow = [Empty | x <- [0..7]]
emptyBoard = [emptyRow | x <- [0..7]]

pieceAt :: Board -> Int -> Int -> Piece
pieceAt board row column = (board !! row) !! column

replace :: [a] -> a -> Int -> [a]
replace (x:xs) el 0 = (el:xs)
replace (x:xs) el index = replace xs el (index-1)

putPieceAt :: Board -> Piece -> Int -> Int -> Board
putPieceAt board piece rowIndex column =
  let oldRow = board !! rowIndex
      newRow = replace oldRow piece column
  in
   replace board newRow rowIndex
   
rowIsEmpty :: [Piece] -> Bool
rowIsEmpty [] = True
rowIsEmpty (p:ps) =
  case p of
    Empty -> rowIsEmpty ps
    _ -> False

-- the moves possible for the piece at row, column
nextMoves board row column =
  case pieceAt board row column of
    Rook -> []
    Empty -> []
    _ -> error "Not implemented yet!"

main = putStrLn "hello world"