将自定义数据类型列表从Haskell传递到C ++

Question

我正在使用foreign export ccall将Haskell函数用于C ++程序。

将基本类型从一种语言传递到另一种语言很容易，但是如何传递更复杂的类型，如下所示：

piecesList::[Piece]
piecesList = [Piece _type _color _coords, ..., ... Piece _type _color _coords]

with：

data Piece = Piece {
  _type :: PieceType,
  _color :: PieceColor,
  _position :: Position
} deriving Eq

data PieceColor = Black | White deriving Eq
data PieceType = Rook | Knight | Bishop | King | Queen | Pawn deriving Eq
type Position = (Int, Int)

如果我这样做（例如）：

get_piecesList::[Piece]
get_piecesList = piecesList

和

foreign export ccall get_piecesList :: [Piece]

我得到了：

 Unacceptable result type in foreign declaration:
    ‘[Piece]’ cannot be marshalled in a foreign call
• When checking declaration:
    foreign export ccall "get_piecesList" get_piecesList :: [Piece]

如何传递此类数据，如何在c ++中处理？

谢谢