Question

我正在阅读LYAH后在Haskell写一个基于文本的冒险游戏，但我需要帮助编写一个函数，其中访问两个数据结构（在这种情况下是两个玩家）和另一个结构（另一个[攻击]玩家）被退回。谢谢！

data Player = Player { name :: String
                 , hp :: Int
                 , atk :: Int
                 , def :: Int
                 , spd :: Int
                 } deriving (Show, Eq)

data Qstat = Qstat Int Int Int Int

lv :: Qstat
lv = Qstat 1 1 1 1

describe :: Player -> String
describe (Player {name = n, hp = h, atk = a, def = d, spd = s}) 
    =    "Name: "  ++ n
      ++ ", HP: "  ++ (show h)
      ++ ", ATK: " ++ (show a)
      ++ ", DEF: " ++ (show d)
      ++ ", SPD: " ++ (show s)

promote :: Qstat -> Player -> Player
promote (Qstat w x y z) (Player {name = n, hp = h, atk = a, def = d, spd = s})
    = Player n (h + w) (a + x) (d + y) (s + z)

gets :: Player -> Qstat
gets (Player {name = n, hp = h, atk = a, def = d, spd = s})
    = Qstat n h a d s

attack :: Player -> Player -> Player
attack = --how can I access the stats of both players (preferably without do notation)

Answer 1

模式匹配或任何（很多）其他方法可以编写双参数函数？此外，您还有各种语法，仅适用于记录类型。

attack :: Player -> Player -> Player
attack aggressor defender = victim { hp = max 0 $ hp victim - dmg }
 where
    aQual = atk aggressor + spd aggressor
    dQual = def defender + spd defender
    (victor, victim) = case compare aQual dQual of
     LT -> (defender, aggressor)
     _  -> (aggressor, defendor)
    dmg = max 1 $ atk victor - def victim

请在发布SO之前进行研究。 3个“标准”初学者文本已经解释了这一点。

访问多个数据结构

1 个答案: