Haskell中的运行时错误 [英] runtime error in Haskell

问题描述

我的程序是在元组列表中搜索<​​/ strong>我将它写成如下

  import List 
 data BookInfo = Book Int String [String] 
 deriving（Show）
 
 enter :: Int-> String-> [String]  - > BookInfo 
输入id名称subject = Book id名称subject 
 bookId（Book id __）= id 
 
 index :: BookInfo  - > Int 
 index（Book id name subject）= bookId（Book id name subject）
 
 arrayentering :: BookInfo-> [BookInfo]  - > [BookInfo] 
 arrayentering（本书编号名称主题）[] = [（书目编号名称主题）] 
 arrayentering（Book _[]）[] = [] 
 arrayentering（Book id name subject）[ （Book id name subject）：[（Book it name suject）] 
 toList :: [BookInfo]  - > [Int] 
 toList [（Book id名称主题）] =地图索引[（书名ID主题）] 
 
 bubbleSort：:( Ord t）=>如果x  else y：[t]  - > [t] 
 bubbleSort [x，y，z，xs] = 
 [ x，z，xs] 
 
 superBubble：:( Ord t）=> [[t]]  - > [[t]] 
 superBubble a =地图bubbleSort a 
 
合并:: [BookInfo]  - > [[Int]] 
合并[（Book id name subject）] = superBubble [toList [（Book id name subject）]] 
  

并清除它从任何语法错误，但在我尝试进入一个元组清单组合（）它给我运行时错误说

例外：在函数Main.combining中没有详尽的模式

这是什么意思？ / p>

请给我说明。如果可能的话，我想自己修复它。

 结合[（Book id name subject）] = superBubble [toList [（Book id name subject）]] 
  

仅与仅包含一个元素的列表匹配。在 bubbleSort 中有类似的问题，其中



  bubbleSort [x， y，z，xs] = 
  

仅匹配包含四个元素和其他地方的列表。

我还没有弄清楚你打算如何工作，或许使用了一个变量模式（匹配所有参数）

 合并books = superBubble（toList books）
  

会是合适的吗？

---

我怀疑

  arrayentering :: BookInfo-> [BookInfo]  - > [BookInfo] 
 arrayentering（Book id name subject）[] = [（Book id name subject）] 
 arrayentering（Book _ [书籍编号名称主题] [（Book it namr suject）] = 
（书目编号名称主题）：[（Book it name suject）] 
  

实际上应该是

  arrayentering book bookList 
 |空书= bookList 
 |否则= book：bookList 
其中
空（Book _ name subject）= all是空格名称&& all（all isSpace）subject 
  

（ empty 可能是错误的）。

和 toList 应该只是 map index 。

My program is searching in list of tuples I wrote it as the following

import List
data BookInfo = Book Int String [String]
  deriving(Show)

enter :: Int->String->[String]->BookInfo
enter id name subject=Book id name subject
bookId   (Book id _     _  ) = id

index :: BookInfo -> Int
index (Book id name subject) =  bookId  (Book id name subject) 

arrayentering ::BookInfo->[BookInfo]->[BookInfo]
arrayentering (Book id name subject) [] =[(Book id name subject)]
arrayentering (Book  _  "     " ["    "]) [] =[]
arrayentering (Book id name subject) [(Book it namr suject)]=                         
              (Book id name subject):[(Book it name suject)]
toList::[BookInfo]->[Int]
toList [(Book id name subject) ]=   map index [ (Book id name subject)]

bubbleSort::(Ord t) => [t]->[t]
bubbleSort[x,y,z,xs]=
                if x<y then x : [y,z,xs]
                       else y : [x,z,xs]

superBubble::(Ord t) => [[t]]->[[t]]
superBubble a=map bubbleSort a

combining::[BookInfo]->[[Int]]
combining [(Book id name subject)]=superBubble [toList [(Book id name subject)]]

and clean it from any syntax error but after i try to enter to a list of tuple to combining() it gve me runtime error say

Exception:Not Exhaustive pattern in function Main.combining

What does this mean?

Please, give me only instructions. If possible, I would like to fix it by my self.

解决方案

The pattern in the function definition

combining [(Book id name subject)]=superBubble [toList [(Book id name subject)]]

matches only lists with exactly one element. You have a similar problem in bubbleSort, where

bubbleSort[x,y,z,xs]=

matches only lists with exactly four elements and elsewhere.

I haven't figured out how you intend it to work, perhaps using a variable pattern (that matches all arguments)

combining books = superBubble (toList books)

would be appropriate?

---

I suspect

arrayentering ::BookInfo->[BookInfo]->[BookInfo]
arrayentering (Book id name subject) [] =[(Book id name subject)]
arrayentering (Book  _  "     " ["    "]) [] =[]
arrayentering (Book id name subject) [(Book it namr suject)]=                         
              (Book id name subject):[(Book it name suject)]

should really be

arrayentering book bookList
    | empty book = bookList
    | otherwise  = book : bookList
      where
        empty (Book _ name subject) = all isSpace name && all (all isSpace) subject

(empty may be wrong).

And toList should probably be just map index.

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