派生代数数据类型的显示

Question

我有以下类型：

data Suit = Club | Diamond | Heart | Spade deriving Show
data Rank = R2 | R3 | R4 | R5 | R6 | R7 | R8 | R9 | R10 | Jack | Queen | King | Ace deriving Show
data JokerColor = Red | Black deriving Show
data JCard = NormalCard Suit Rank | JokerCard JokerColor

如何显示JCard？目前我得到的是No instance for (Show JCard)

Answer 1

只需以与JokerColor相同的方式为JCard派生show。

data JokerColor = Red | Black deriving Show
data JCard = NormalCard Suit Rank | JokerCard JokerColor deriving Show

对于大多数类型，人们通常会派生Eq、Ord和Show。