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尝试处理 JSON 数据时,haskell 中的初学者问题。

我有一个名为kk的简单文件,其内容如下:

{
 "id": 123,
 "name": "Test1"
}

我正在使用以下代码成功读取和解析它:

{-# LANGUAGE OverloadedStrings #-}

import Data.Aeson
import Data.Aeson.Types
import Control.Applicative ((<$>), (<*>))
import Control.Monad
import qualified Data.ByteString.Lazy.Char8 as BS

data Test = Test { id       ∷ Integer
                 , name     ∷ String
                 } deriving (Show)


process v = Test <$>
                 (v .: "id")       <*>
                 (v .: "name")


instance FromJSON Test where
  parseJSON (Object o) = process o
  parseJSON (Array  a)  = mzero
  parseJSON _ = mzero

main = do
    src ← readFile "kk"
    let t = decode (BS.pack src) ∷ Maybe Test
    print t

但是,如果它是一个数组,我似乎无法确定我应该如何处理该文件,这意味着:

[{
 "id": 1,
 "name": "Test1"
},
{
 "id": 2,
 "name": "Test2"
}]

如何折叠或以其他方式迭代数组案例?

4

1 回答 1

4

尝试

let t = decode (BS.pack src) :: Maybe [Test]
于 2013-01-20T19:16:40.263 回答