rib

Rib is a Haskell static site generator that aims to reuse existing libraries instead of reinventing the wheel.

How does it compare to Hakyll?

• Uses the Shake build system at its core.
• Allows writing Haskell DSL to define HTML (Lucid) & CSS (Clay)
• Built-in support for Pandoc and MMark, while also supporting custom parsers (eg: Dhall, TOML)
• Remain as simple as possible to use (see example below)
• Nix-based environment for reproducibility
• ghcid and fsnotify for "hot reload"

Rib prioritizes the use of existing tools over reinventing them, and enables the user to compose them as they wish instead of having to write code to fit a custom framework.

Table of Contents

• rib
  • Quick Preview
  • Getting Started
  • Concepts
    • Directory structure
    • Run the site
    • How Rib works
    • Editing workflow
    • What's next?
  • Examples

Quick Preview

Here is how your code may look like if you were to generate your static site using Rib:

-- | Route corresponding to each generated static page.
--
-- The `a` parameter specifies the data (typically Markdown document) used to
-- generated the final page text.
data Route a where
  Route_Index :: Route ()
  Route_Article :: ArticleRoute a -> Route a

-- | You may even have sub routes.
data ArticleRoute a where
  ArticleRoute_Index :: ArticleRoute [(Route MMark, MMark)]
  ArticleRoute_Article :: Path Rel File -> ArticleRoute MMark

-- | The `IsRoute` instance allows us to determine the target .html path for
-- each route. This affects what `routeUrl` will return.
instance IsRoute Route where
  routeFile = \case
    Route_Index ->
      pure [relfile|index.html|]
    Route_Article r ->
      fmap ([reldir|article|] </>) $ case r of
        ArticleRoute_Article srcPath ->
          replaceExtension ".html" srcPath
        ArticleRoute_Index ->
          pure [relfile|index.html|]

-- | The "Config" type generated from the Dhall type.
--
-- Use `Rib.Parser.Dhall` to parse it (see below).
makeHaskellTypes
  [ SingleConstructor "Config" "Config" "./src-dhall/Config.dhall"
  ]

-- | Main entry point to our generator.
--
-- `Rib.run` handles CLI arguments, and takes three parameters here.
--
-- 1. Directory `content`, from which static files will be read.
-- 2. Directory `dest`, under which target files will be generated.
-- 3. Shake action to run.
--
-- In the shake action you would expect to use the utility functions
-- provided by Rib to do the actual generation of your static site.
main :: IO ()
main = Rib.run [reldir|content|] [reldir|dest|] generateSite

-- | Shake action for generating the static site
generateSite :: Action ()
generateSite = do
  -- Copy over the static files
  Rib.buildStaticFiles [[relfile|static/**|]]
  -- Read the site config
  config :: Config <-
    Dhall.parse
      [[relfile|src-dhall/Config.dhall|]]
      [relfile|config.dhall|]
  let writeHtmlRoute :: Route a -> a -> Action ()
      writeHtmlRoute r = writeRoute r . Lucid.renderText . renderPage config r
  -- Build individual sources, generating .html for each.
  articles <-
    Rib.forEvery [[relfile|*.md|]] $ \srcPath -> do
      let r = Route_Article $ ArticleRoute_Article srcPath
      doc <- MMark.parse srcPath
      writeHtmlRoute r doc
      pure (r, doc)
  writeHtmlRoute (Route_Article ArticleRoute_Index) articles
  writeHtmlRoute Route_Index ()

-- | Define your site HTML here
renderPage :: Config -> Route a -> a -> Html ()
renderPage config route val = with html_ [lang_ "en"] $ do
  head_ $ do
    meta_ [httpEquiv_ "Content-Type", content_ "text/html; charset=utf-8"]
    title_ $ routeTitle
    style_ [type_ "text/css"] $ C.render pageStyle
  body_ $ do
    with div_ [id_ "thesite"] $ do
      with div_ [class_ "header"] $
        with a_ [href_ "/"] "Back to Home"
      h1_ routeTitle
      case route of
        Route_Index ->
          p_ $ do
            "This site is work in progress. Meanwhile visit the "
            with a_ [href_ $ routeUrl $ Route_Article ArticleRoute_Index] "articles"
            " page."
        Route_Article ArticleRoute_Index ->
          div_ $ forM_ val $ \(r, src) ->
            with li_ [class_ "pages"] $ do
              let meta = getMeta src
              b_ $ with a_ [href_ (Rib.routeUrl r)] $ toHtml $ title meta
              maybe mempty renderMarkdown $ description meta
        Route_Article (ArticleRoute_Article _) ->
          with article_ [class_ "post"] $ do
            MMark.render val
  where
    routeTitle :: Html ()
    routeTitle = case route of
      Route_Index -> toHtml $ siteTitle config
      Route_Article (ArticleRoute_Article _) -> toHtml $ title $ getMeta val
      Route_Article ArticleRoute_Index -> "Articles"
    renderMarkdown =
      MMark.render . either (error . T.unpack) id . MMark.parsePure "<none>"

-- | Define your site CSS here
pageStyle :: Css
pageStyle = "div#thesite" ? do
  C.margin (em 4) (pc 20) (em 1) (pc 20)
  ".header" ? do
    C.marginBottom $ em 2
  "li.pages" ? do
    C.listStyleType C.none
    C.marginTop $ em 1
    "b" ? C.fontSize (em 1.2)
    "p" ? sym C.margin (px 0)

-- | Metadata in our markdown sources
data SrcMeta
  = SrcMeta
      { title :: Text,
        -- | Description is optional, hence `Maybe`
        description :: Maybe Text
      }
  deriving (Show, Eq, Generic, FromJSON)

-- | Get metadata from Markdown's YAML block
getMeta :: MMark -> SrcMeta
getMeta src = case MMark.projectYaml src of
  Nothing -> error "No YAML metadata"
  Just val -> case fromJSON val of
    Aeson.Error e -> error $ "JSON error: " <> e
    Aeson.Success v -> v

(View full Main.hs at rib-sample)

Getting Started

The easiest way to get started with Rib is to use the template repository, rib-sample, from Github.

Concepts

Directory structure

Let's look at what's in the template repository:

$ git clone https://github.com/srid/rib-sample.git mysite
...
$ cd mysite
$ ls -F
a/  default.nix  Main.hs  README.md  rib-sample.cabal

The three key items here are:

1. Main.hs: Haskell source containing the DSL of the HTML/CSS of your site.
2. a/: The source content (eg: Markdown sources and static files)
3. b/: The target directory, excluded from the git repository, will contain generated content (i.e., the HTML files, and copied over static content)

The template repository comes with a few sample posts under a/, and a basic HTML layout and CSS style defined in Main.hs.

Run the site

Now let's run them all.

Clone the sample repository locally, install Nix and run your site as follows:

nix-shell --run 'ghcid -T main'

(Note even though the author recommends it Nix is strictly not required; you may simply run ghcid -T main instead of the above command if you do not wish to use Nix.)

Running this command gives you a local HTTP server at http://localhost:8080/ (serving the generated files) that automatically reloads when either the content (a/) or the HTML/CSS/build-actions (Main.hs) changes. Hot reload, in other words.

How Rib works

How does the aforementioned nix-shell command work?

1. nix-shell will run the given command in a shell environment with all of our dependencies (notably the Haskell ones including the rib library itself) installed.

2. ghcid will compile your Main.hs and run its main function.

3. Main.hs:main in turn calls Rib.App.run which takes as argument your custom Shake action that will build the static site.

4. Rib.App.run: this parses the CLI arguments and runs the rib CLI "app" which can be run in one of a few modes --- generating static files, watching the a/ directory for changes, starting HTTP server for the b/ directory. By default---without any explicit arguments---this will run the Shake build action passed as argument on every file change and spin up a HTTP server.

Run that command, and visit http://localhost:8080 to view your site.

Editing workflow

Now try making some changes to the content, say a/first-post.md. You should see it reflected when you refresh the page. Or change the HTML or CSS of your site in Main.hs; this will trigger ghcid to rebuild the Haskell source and restart the server.

What's next?

Great, by now you should have your static site generator ready and running! What more can you do? Surely you may have specific needs; and this usually translates to running custom Shake actions during the build. Rib provides helper functions in Rib.Shake to make this easier.

Rib recommends writing your Shake actions in the style of being forward-defined which adds to the simplicity of the entire thing.

Examples

• rib-sample: Use this to get started with your own site.

• Author's own website. Live at https://www.srid.ca/