使用Aeson解析Haskell中的嵌套JSON

我正在努力学习哈斯克尔的伊森图书馆。 现在我正试图解析一个简单的JSON文件，如下所示

{
    "Meta Data": {
        "1: Symbol": "MSFT",
        "2: Indicator": "Relative Strength Index (RSI)",
        "3: Last Refreshed": "2018-10-15",
        "4: Interval": "weekly",
        "5: Time Period": 10,
        "6: Series Type": "open",
        "7: Time Zone": "US/Eastern Time"
    },
    "Technical Analysis: RSI": {
        "2018-10-15": {
            "RSI": "54.5653"
        },
        "2018-10-12": {
            "RSI": "63.0279"
        },
        "2018-10-05": {
            "RSI": "74.7519"
        },
        "2018-09-28": {
            "RSI": "72.1573"
        },
        "2018-09-21": {
            "RSI": "74.8123"
        },
        "2018-09-14": {
            "RSI": "66.7116"
        },
        "2018-09-07": {
            "RSI": "75.8051"
        },
..and so on

借助本Aeson教程 特别是“嵌套记录”部分

---

这就是我到目前为止得到的

{-# LANGUAGE DeriveGeneric     #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE RecordWildCards   #-}

module Tesst where

import           Data.Aeson
import qualified Data.ByteString.Lazy as B
import           Data.Time
import           GHC.Exts
import           GHC.Generics
import           Network.HTTP.Conduit (simpleHttp)

data TechinicalAnalysis = TechinicalAnalysis {
                   name :: String,
                   date :: String,
                   rsi  :: String
                   } deriving (Show, Generic)


instance FromJSON TechinicalAnalysis where
  parseJSON = withObject "RSI Quote" $
    \o -> do
      rsiQuote <- o        .: "Technical Analysis: RSI"
      date     <- rsiQuote .: "2018-10-16"
      rsi      <- date     .: "RSI"
      return TechinicalAnalysis {..}


main :: IO ()
main = do
  putStrLn "Which ticker? "
  symbolToQuote <- getLine
  d <- (eitherDecode <$> simpleHttp ("https://www.alphavantage.co/query?function=RSI&interval=weekly&time_period=10&series_type=open&apikey==FI2KMCSDSAE&symbol=" ++ symbolToQuote)) :: IO (Either String TechinicalAnalysis)
  case d of
    Left e   -> print e
    Right qt -> print (rsi qt)

我想这是在告诉我从

date得到的
date
响应解决了问题

返回的内容：
返回的类型为
对象
，而不是
字符串

所以不是这个

data TechinicalAnalysis = TechinicalAnalysis {
                   name :: String,
                   date :: String,
                   rsi  :: String
                   } deriving (Show, Generic)

我对此感到愤怒

newtype TechinicalAnalysis = TechinicalAnalysis {
                   rsi  :: String
                   } deriving (Show, Generic)

而且它工作得天衣无缝
 您是否尝试过
return（TechinicalAnalysis{..}）
或
return$TechinicalAnalysis{..}
？@MarkSeemann刚刚尝试过，运气不好：（出现了相同的错误）
newtype TechinicalAnalysis = TechinicalAnalysis {
                   rsi  :: String
                   } deriving (Show, Generic)