Question

我正在尝试构建this Hakyll blog。在尝试编译site.hs时，网站构建计划......

root@AR:/usr/local# git clone https://github.com/relrod/blog elrod.me
root@AR:/usr/local# cd elrod.me
root@AR:/usr/local/elrod.me# ghc --make site.hs

...我收到以下类型错误：

[1 of 1] Compiling Main ( site.hs, site.o ) site.hs:28:70: error:
  Couldn't match type ‘unordered-containers-0.2.7.2:Data.HashMap.Base.HashMap Data.Text.Internal.Text aeson-1.1.0.0:Data.Aeson.Types.Internal.Value’ with ‘M.Map [Char] a1’
  Expected type: M.Map [Char] a1
    Actual type: Metadata

  In the third argument of ‘M.findWithDefault’, namely ‘metadata’
  In the expression: M.findWithDefault "No title" "title" metadata
  In an equation for ‘title’: title = M.findWithDefault "No title" "title" metadata

  Relevant bindings include title :: a1 (bound at site.hs:28:25)

我该如何解决？以下是site.hs的相关部分：

{-# LANGUAGE OverloadedStrings #-}
import qualified Data.Map as M
import Data.Monoid ((<>))
import Hakyll
import Text.Pandoc.Options (readerSmart)

main :: IO ()
main = hakyll $ do
    -- etc.
    match "posts/*" $ do
        route $ setExtension "html"
        compile $ do
            let safetitle = field "safetitle" $ \item -> do
                    metadata <- getMetadata (itemIdentifier item)
                    let title = M.findWithDefault "No title" "title" metadata
                    return $ concatMap (\x -> if x == '\'' then "\\'" else [x]) title
            pandocCompilerWith defaultHakyllReaderOptions {readerSmart = False} defaultHakyllWriterOptions
                >>= saveSnapshot "content"
                >>= loadAndApplyTemplate "templates/post.html"    (postCtx tags <> safetitle)
                >>= loadAndApplyTemplate "templates/default.html" defaultContext
                >>= relativizeUrls
   -- etc.

Answer 1

这里的问题是{hansll的版本Metadata之后4.4.2.0的表示已经发生了变化（您正在尝试构建的项目.cabal的下限）。< / p>

在4.4.2.0中，Metadata is a Map String String

在4.9.5.0（最新版）中，Metadata is an Object。

您需要使用较旧版本的Hakyll（例如，在.cabal文件中添加上限以确保Metadata的表示与版本4.4.2.0中的表示匹配）或更新代码考虑到较新的界面并碰撞下限。

在构建网站时输入涉及HashMap和Map的错误

1 个答案: