S6T5 - to use inter link in md with modified Route by Hakyll

lang	en	ja

Published	Last Update	author
2024/05/28	2024/05/28	Shumpei Tanaka

links in output html are not updated automatically via Hakyll’s pandoc compiler with modified route.

For this reason, it is necessary to manually rewrite the link in markdown.

withUrls is a function in Hakyll can apply String->String convert in each URLs.

so it can be used to create a specific parser.

below is usage example.

parseInnerLinks: apply parseInnerLink each URLs by withUrls.
parseInnerLink: apply parsePostLink only URL has prefix /posts

parseInnerLinks :: Item String -> Compiler (Item String)
parseInnerLinks = pure . fmap (withUrls parseInnerLink)

parseInnerLink :: String -> String
parseInnerLink url
    | isExternal url = url
    | "/posts" `L.isPrefixOf` url =
        parsePostLink url
    | otherwise =
        url

parsePostLink: it convert URL which include # (section link). convert URL before # and re-concat URL after #.
convPostUrl: apply String->String convert in same as used Route delete / which head of URL by tail to get Filepath.

parsePostLink :: String -> String
parsePostLink url = case map T.unpack . T.splitOn "#" $ T.pack url of
    [base] -> addHtml . convPostUrl $ base
    [base, section] -> (++ section) . (++ "#") . addHtml . convPostUrl $ base

convPostUrl :: String -> String
convPostUrl url = (++) "/" . getLangPath . fromFilePath $ tail url

addHtml :: String -> String
addHtml = (++ ".html")

below is example of usage parseInnerLinks.

pandocCompiler
    >>= loadAndApplyTemplate "templates/post.html" postCtx
    >>= loadAndApplyTemplate "templates/default.html" postCtx
    >>= parseInnerLinks
    >>= relativizeUrls