S6T5 - to build multi lang site with Hakyll

lang	en	ja

Published	Last Update	author
2024/05/25	2024/05/28	Shumpei Tanaka

multi-lang by file base

Create a multi-lang site by writing articles with the following structure.

posts/2024-05-28-filename-en.md
posts/2024-05-28-filename-jp.md

specific example

This site is being created with the above structure. The engine part will be separated and released at a later date.

modify Route

First, change the Route. The following is an image of the change.

path: original source
- posts/2024-05-28-filename-en.md
- posts/2024-05-28-filename-jp.md
path: converted html
- en/2024-05-28-filename.html
- jp/2024-05-28-filename.html

Excerpt : codes of Route

match (fromArticle "posts/*") $ do
    route langRoute

langRoute :: Routes
langRoute = customRoute ((`replaceExtension` ".html") . getLangPath)

langseperator :: String
langseperator = "-"

takeLang :: Identifier -> String
takeLang = last . splitAll langseperator . takeBaseName . toFilePath

dropLang :: Identifier -> String
dropLang = L.intercalate langseperator . init . splitAll langseperator . toFilePath

getLangPath :: Identifier -> String
getLangPath id = lang `combine` dropLang id
  where
    lang = takeLang id

The operations being performed are simple and include the following

get filepath from Identifier
pick lang-code such as like -en, -jp
swap and re-concat with /

embed link which another lang

It is achieved as follows.

search same filename from Identifier such as :filename-lang.md
put link which search result

anothorLangFields :: String -> Snapshot -> Context String
anothorLangFields name snapshot = listFieldWith name baseCtx f
  where
    f item = loadAllSnapshots (fromGlob (mainname ++ "*")) snapshot
      where
        id = itemIdentifier item
        mainname = dropLang id
        lang = takeLang id

below is how to use anothorLangFields.

make snapshot
apply template with postCtx

match (fromArticle "posts/*") $ do
    route langRoute
    compile $ do
        pandocCompiler
            >>= saveSnapshot "posts-content"
            >>= loadAndApplyTemplate (idBase "templates/post.html") postCtx

postCtx is to connect baseCtx and anothorLangFields.

postCtx :: Context String
postCtx =
    baseCtx
        `mappend` anothorLangFields "anothorLangs" "posts-content"

baseCtx : a context to embed basic info

baseCtx :: Context String
baseCtx =
    dateField "date" "%Y/%m/%d"
        `mappend` dateFieldMeta "last-modified" "last-modified" "%Y/%m/%d"
        `mappend` readTimeField "readtime" "posts-content"
        `mappend` langField "lang"
        `mappend` sameLangField "home" "index"
        `mappend` defaultContext

The context now has the following structure

date
last-modified
readtime
lang
home
(defaultContext)
anotherlangs
- date
- last-modified
- readtime
- lang
- home
- (defaultContext)

It can be called as like below in template.

$for(anothorLangs)$
<tr>
    <td>
        <a href="$url$">$title$ ($lang$)</a>
    </td>
    <td>$date$</td>
    <td>$if(last-modified)$ $last-modified$ $else$ $date$ $endif$</td>
</tr>
$endfor$

to use inter link in md with modified `Route`

This is separated into a separate page due to its more general content.

to use inter link in md with modified Route by Hakyll

to reconstruct post list

-en.md and -jp.md will be lined up respectively if posts/*.md read in this file-based system.

but necessary is unieque one of same file in posts/file-lang.md.

apply filterUniqs againstposts/* like the following and save only unique file.

compile $ do
    posts <- recentFirst . filterUniqs =<< loadAllSnapshots "posts/*" "posts-content"

filterUniqs is a function to reconstruct [Item String]. pick files which filename dropped a part -lang is not same. and concat picked items. and make a list to concated it.

filterUniqs :: [Item String] -> [Item String]
filterUniqs [] = []
filterUniqs (x : xs) = x : filterUniqs (filter ((/= f x) . f) xs)
  where
    f = dropLang . itemIdentifier

This will achieve the expected operation.