无法将类型`[]'与`IO' - Haskell匹配 [英] Couldn't match type `[]' with `IO' -- Haskell

问题描述

我是Haskell的初学者。在这个任务我执行拆分操作，但我面临的问题，因为类型不匹配。我从文本文件读取数据，数据是表格式。例如， 1 | 2 | Rahul | 13.25。在此格式中。这里 | 是分隔符，因此我想从分隔符 | 拆分数据，并打印第2列和第4列数据但我得到这样的错误

 无法与`IO'匹配类型`[]'
预期类型：IO [Char] 
实际类型：[[Char]] 
在splitOn的调用的返回类型中
  pre> 
 
 
这是我的代码.. 
  b 
 $ b import Data.List.Split 
 
 main = do 
 list<  -  readFile（src / table.txt）
 putStrLn list 
 splitOn| list 
  
任何有关这方面的帮助都会感谢。感谢
解决方案
问题是你试图从 main 函数返回一个列表， code> IO（）。
 
 
 
您可能想要打印的结果。
  main = do 
 list<  -  readFile（src / table.txt）
 putStrLn list 
 print $ splitOn | list 
  
 
I'm beginner in Haskell. In this task i'm performing the split operation but i'm facing problem because of type mis match. I'm reading data from text file and the data is in table format. Ex. 1|2|Rahul|13.25. In this format. Here | is delimiter so i want to split the data from the delimiter | and want to print 2nd column and 4th column data but i'm getting the error like this 
  "Couldn't match type `[]' with `IO'
    Expected type: IO [Char]
      Actual type: [[Char]]
    In the return type of a call of `splitOn'"
Here is my code..
module Main where

import Data.List.Split

main = do
    list <- readFile("src/table.txt")
    putStrLn list
    splitOn "|" list
Any help regarding this will appreciate.. Thanks
解决方案
The problem is that you're trying to return a list from the main function, which has a type of IO ().

What you probably want to do is print the result.
main = do
    list <- readFile("src/table.txt")
    putStrLn list
    print $ splitOn "|" list


                        
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