Coursera编程语言hw2

Question

fun officiate (clist , mlist , score) =
    let val hlist = []
    in
      let
        fun appendh ([], _, score) = hlist
          | appendh (_, [], score) = hlist 
          | appendh (c :: clist', m :: mlist', score) = 
        case (sum_cards(hlist) > score, m) of
            (true, _) => hlist
          | (false, Draw) => c :: appendh(clist', mlist', score)
          | (false, Discard a) => remove_card(hlist, a, IllegalMove) @ appendh(clist', mlist', score)                            
      in
        score(appendh(clist, mlist, score), score)
      end
    end

// val officiate = fn：卡列表*移动列表* int-> int

// val分数= fn：卡片列表* int-> int

当我使用此功能时，发现了这个错误：

---

• 使用“ hw2.sml”；[打开hw2.sml]hw2.sml：137.6-137.48错误：运算符不是函数[tycon不匹配]运算子：int表达：得分（附录（clist，mlist，得分），得分）val it =（）：单位

  ---

我之前设置的数据类型：

---

datatype suit = Clubs | Diamonds | Hearts | Spades
datatype rank = Jack | Queen | King | Ace | Num of int 
type card = suit * rank

datatype color = Red | Black  (*spades  and  clubs  are  black,diamonds and hearts are red)*) 
datatype move = Discard of card | Draw 

exception IllegalMove

---

并且我使用之前创建的得分函数，它可以正常工作：

fun score (xs, score) =   
    let val sum = sum_cards(xs)
    in
       case (all_same_color(xs), sum > score) of
            (true, true) => (3 * (sum - score)) div 2
          | (true, false) => (score - sum) div 2
          | (false, true) => 3 * (sum - score)
          | (false, false) => score - sum
    end

Answer 1

我知道了，我可以使用变量score这是得分函数。