------------------------------------------------------------------------------
checkCastleBB :: Colour -> Castle -> BitBoard
checkCastleBB White Long  =
  mconcat [ fromSquare sq
          | sq <- [(toSquare cFile firstRank) .. (toSquare eFile firstRank)]
          ]
checkCastleBB :: Colour -> Castle -> BitBoard
checkCastleBB White Long  =
  mconcat [ fromSquare sq
          | sq <- [(toSquare cFile firstRank) .. (toSquare eFile firstRank)]
          ]
checkCastleBB White Long  =
  mconcat [ fromSquare sq
          | sq <- [(toSquare cFile firstRank) .. (toSquare eFile firstRank)]
          ]