Yeson.json.object 应用于太多参数

Question

import Yesod
import Data.Text

data App = App

instance Yesod App

mkYesod "App" [parseRoutes|
               / Home GET
               |]

getHome :: String -> Handler Value
getHome  =  object ["name" .= ("Adam"::Text)]

main = warpDebug 2012 App

抛出错误，

 Couldn't match expected type ‘String -> Handler Value’
                with actual type ‘Value’
    Possible cause: ‘object’ is applied to too many arguments
    In the expression: object ["name" .= ("Adam" :: Text)]
    In an equation for ‘getHome’:
        getHome = object ["name" .= ("Adam" :: Text)]

object 不在前奏的范围内。哪个 package/module 定义了这个？上例为什么不取键值对？

Answer 1

object is not in scope in prelude. Which package/module defines this?

Yesod.Json

Why doesn't it take the key-value pair in the above case?

接受键值对就好了。错误消息告诉您 object 给了您一个 Value，但您声明 getHome 是 String -> Handler Value 类型，而不是 Value.

在这种情况下，"possible cause" 似乎只是误导。

Yeson.json.object 应用于太多参数

Yeson.json.object is applied to too many arguments

haskell

yesod

classy-prelude