如何用parsec解析yahoo csv [英] how to parse yahoo csv with parsec

问题描述

如何解析数组，例如open [i]，high [i]，low [i]，close [i]

  testhaskell.hs：22：5：
与`IO'类型'[]'不匹配'
期望类型：IO a0 
实际类型：[a0] 
在`map'调用的返回类型中
在'do'块的语句中：map（\ line  - >句子行）allLines 
在表达式中：
 do {handle < -  openFile 
C：\\ Users \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\ 
 
内容<  -  hGetContents句柄; 
 let allLines =行内容; 
 map（\ line  - >句子行）allLines; 
 ....} 
 
 testhaskell.hs：22：19：
无法匹配期望的类型`String  - > a0'
与实际类型`Text.Parsec.Prim.ParsecT 
 String（）Data.Functor.Identity.Identity [String]'
  

$ b $ import System.IO
导入限定数据。 ByteString.Char8 as BS
将合格的Data.ByteString导入为Str
import Text.ParserCombinators.Parsec

word :: Parser String
word = many1 letter

sentence：Parser [String]
sentence = do {words< - sepBy1 word separator
; oneOf。？！ <？> 句尾
;返回单词


separator :: Parser（）
separator = skipMany1（space< |> char'，'<>）

main = do
handle < - openFileC：\\ Users \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\内容< - hGetContents句柄
let allLines =行内容
map（\ line - >句子行）allLines
--putStr内容
hClose句柄


更新：

 模块Main其中
 
将合格的Data.ByteString.Char8导入为B 
导入Data.Map（（！））
导入Data.Text 
将合格的Data.Vector导入为V 
 import System.Directory 
 import Test.Framework（Test，defaultMain，testGroup）
 import Test.Framework.Providers.API 
 import Tes t.HUnit（（@ =？））
 
 import Data.CSV.Conduit 
 
 $ b $ main :: IO（）
 main = defaultMain测试
 
 
 tests :: [Test] 
 tests = [testGroupBasic OpsbaseTests] 
 
 
 baseTests :: [Test] 
 baseTests = 
 [
 testCasesimple parsing workstest_simpleParse 
] 
 
 
 test_simpleParse :: IO（）
 test_simpleParse = do 
（d :: V.Vector（MapRow B.ByteString））<  -  readCSVFile csvSettings testFile1 
 V.mapM_ assertRow d 
其中
 assertRow r = v3 @ = ？ （v1 + v2）
其中v1 = readBS $ r！ 打开
 v2 = readBS $ r！ 高
 v3 = readBS $ r！ 低
 v4 = readBS $ r！ Close
 
 
 csvSettings :: CSVSettings 
 csvSettings = defCSVSettings {csvQuoteChar =只是'`'} 
 
 testFile1 :: FilePath 
 testFile1 =C：\\Users\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\' ; Int 
 readBS = read。 B.unpack 
  

testhaskell.hs：52：5：不在范围内：`testCase'

testhaskell.hs：58：9：
非法类型签名：`V.Vector（MapRow B.ByteString）'
也许您打算使用-XScopedTypeVariables
在模式类型签名中

解决方案

我强烈建议您不要做这个。 Hackage上有许多高质量的CSV库，并且自己推出是一个问题。在FP完成时，我们使用 csv-conduit ，但木薯也是一个很棒的图书馆。我建议你尝试一下。

how to parse into array such as open[i],high[i],low[i],close[i]

testhaskell.hs:22:5:
    Couldn't match type `[]' with `IO'
    Expected type: IO a0
      Actual type: [a0]
    In the return type of a call of `map'
    In a stmt of a 'do' block: map (\ line -> sentence line) allLines
    In the expression:
      do { handle <- openFile
                       "C:\\Users\\ivan\\Downloads\\0388.HK.csv" ReadMode;

           contents <- hGetContents handle;
           let allLines = lines contents;
           map (\ line -> sentence line) allLines;
           .... }

testhaskell.hs:22:19:
    Couldn't match expected type `String -> a0'
                with actual type `Text.Parsec.Prim.ParsecT
                                    String () Data.Functor.Identity.Identity [String]'

import System.IO 
import qualified Data.ByteString.Char8 as BS
import qualified Data.ByteString as Str
import Text.ParserCombinators.Parsec

word    :: Parser String
word    = many1 letter

sentence    :: Parser [String]
sentence    = do{ words <- sepBy1 word separator
                ; oneOf ".?!" <?> "end of sentence"
                ; return words
                }

separator   :: Parser ()
separator   = skipMany1 (space <|> char ',' <?> "")

main = do  
    handle <- openFile "C:\\Users\\ivan\\Downloads\\0005.HK.csv" ReadMode  
    contents <- hGetContents handle  
    let allLines = lines contents
    map (\line -> sentence line) allLines
    --putStr contents  
    hClose handle

update:

module Main where

import qualified Data.ByteString.Char8          as B
import           Data.Map                       ((!))
import           Data.Text
import qualified Data.Vector                    as V
import           System.Directory
import           Test.Framework                 (Test, defaultMain, testGroup)
import           Test.Framework.Providers.API
import           Test.HUnit                     ((@=?))

import           Data.CSV.Conduit


main :: IO ()
main = defaultMain tests


tests :: [Test]
tests = [testGroup "Basic Ops" baseTests]


baseTests :: [Test]
baseTests =
  [ 
    testCase "simple parsing works" test_simpleParse
  ]


test_simpleParse :: IO ()
test_simpleParse = do
  (d :: V.Vector (MapRow B.ByteString)) <- readCSVFile csvSettings testFile1
  V.mapM_ assertRow d
  where
    assertRow r = v3 @=? (v1 + v2)
      where v1 = readBS $ r ! "Open"
            v2 = readBS $ r ! "High"
            v3 = readBS $ r ! "Low"
            v4 = readBS $ r ! "Close"


csvSettings :: CSVSettings
csvSettings = defCSVSettings { csvQuoteChar = Just '`'}

testFile1 :: FilePath
testFile1 = "C:\\Users\\ivan\\Downloads\\0005.HK.csv"


readBS :: B.ByteString -> Int
readBS = read . B.unpack

testhaskell.hs:52:5: Not in scope: `testCase'

testhaskell.hs:58:9: Illegal type signature: `V.Vector (MapRow B.ByteString)' Perhaps you intended to use -XScopedTypeVariables In a pattern type-signature

解决方案

I'd strongly recommend you not do this. There are a number of high-quality CSV libraries on Hackage, and rolling your own is a recipe of problems. At FP Complete, we use csv-conduit, though cassava is also a great library. I'd recommend you try out one of them.

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