在Haskell中創建數據類型

Question

我想創建一個新的數據類型，該數據類型可以使用Start或A tuple of values。 這就是我所擁有的：

type Coord = (Int, Int)
data Direction = N | E | S | W
                 deriving (Eq, Show, Read)


type Move = (Coord, Direction)
type BoardSpec = [(Coord, Bool)]

type GameTreeNode = (GameTree2, BoardSpec, Move)
data GameTree2 = Start | GameTreeNode deriving(Show)


blahblah :: GameTree2
blahblah = blahb

blahb :: GameTreeNode
blahb = (Start, testbo, ((1, 1), N))

但是，這給了我錯誤

Couldn't match type `(GameTree2, Move)' with `GameTree2'
Expected type: GameTree2
  Actual type: GameTreeNode

Answer 1

數據GameTree2 =開始| GameTreeNode派生（顯示）

擴展為：

 
 
 
  
  data GameTree2 = Start | (GameTree2, BoardSpec, Move) deriving(Show)
 
  

您不能使元組成為您類型的有效值。

---

您需要將其包裝在構造函數中：

 data GameTree2 = Start | Node GameTreeNode deriving(Show) 

Node是您為其選擇的任何名稱。