我不确定为什么我不能让这个工作....
我的hs文件顶部有QuasiQuotes和OverloadedStrings,位于main.hs,maindevel.hs的顶部,也在我的foo.cabal文件中声明。
错误:
Couldn't match type ‘[Char]’ with ‘Text’
Expected type: Text
Actual type: String
In the second argument of ‘($)’, namely
‘renderHtml (GHC.Base.id (toHtml y))’
In the expression:
putStrLn $ renderHtml (GHC.Base.id (toHtml y))
代码:
module Widgets.MainWidgets where
{-# LANGUAGE GADTs #-}
{-# LANGUAGE QuasiQuotes #-}
{-# LANGUAGE TemplateHaskell #-}
{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE DeriveGeneric #-}
{-# LANGUAGE OverloadedStrings, TypeSynonymInstances, FlexibleInstances #-}
import Import
import Text.Hamlet (shamlet)
import Text.Blaze.Html.Renderer.String (renderHtml)
import Data.Char (toLower)
import Data.List (sort)
import qualified Data.Text as T
import qualified Data.Text.IO as T
import ClassyPrelude
import Yesod
import Data.Time.Clock
import Data.Time.Calendar
import Data.Time.LocalTime
import Data.Time.Format
getCurrYear :: String
getCurrYear = formatTime defaultTimeLocale "%y" getCurrentTime
getYear :: IO ()
getYear = putStrLn $ renderHtml
[shamlet|#{y}|]
where y = getCurrYear
我的foo.cabal文件中也有这个:
extensions: TemplateHaskell
QuasiQuotes
OverloadedStrings
NoImplicitPrelude
CPP
MultiParamTypeClasses
TypeFamilies
GADTs
GeneralizedNewtypeDeriving
FlexibleContexts
EmptyDataDecls
NoMonomorphismRestriction
DeriveDataTypeable
ViewPatterns
TupleSections
RecordWildCards
TypeSynonymInstances
FlexibleInstances
DeriveGeneric
我知道为什么会出现字符串/文本转换错误? 提前致谢! 阿德里安
答案 0 :(得分:3)
ClassyPrelude中的putStrLn采用Text而不是String。最简单的解决方案是将Renderer导入更改为模块的Text版本。