haskell - Haskell 中的运行时错误

Question

我的程序是 在元组列表中搜索 我写成如下

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)]]

并将其从任何语法错误中清除，但在我尝试输入到 combining() 的元组列表之后它给了我运行时错误说
Exception:Not Exhaustive pattern in function Main.combining
这是什么意思？

请只给我指示。如果可能，我想自己修复它。

Answer 1

函数定义中的模式

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

只匹配只有一个元素的列表。您在 bubbleSort 中也有类似的问题， 在哪里

bubbleSort[x,y,z,xs]=

只匹配正好有四个元素的列表和其他地方。

我还没有弄清楚你打算如何工作，也许使用可变模式(匹配所有参数)

combining books = superBubble (toList books)

会合适吗？

我怀疑

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)]

真的应该

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

( empty 可能是错误的)。

和 toList应该只是 map index .