rib/README.md

rib

Rib is a Haskell library for writing your own static site generator.

How does it compare to Hakyll?

• Use the Shake build system
• Builtin support for using Haskell DSL to define the HTML (Lucid) & CSS (Clay) of your site
  • Like Hakyll, Rib uses Pandoc for parsing the source documents. It also supports MMark if you need a lightweight alternative.
• Remain as simple as possible to use (see example below)
• Optional Nix based workflow for easily reproducible environment

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.

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

-- First we shall define two datatypes to represent our pages. One, the page
-- itself. Second, the metadata associated with each document.

-- | A generated page is either an index of documents, or an individual document.
data Page doc
  = Page_Index [Document doc]
  | Page_Doc (Document doc)

-- | Type representing the metadata in our Markdown documents
--
-- Note that if a field is not optional (i.e., not Maybe) it must be present.
data Meta
  = Meta
      { title :: Text,
        description :: Maybe Text
      }
  deriving (Show, Eq, Generic, FromJSON)

-- | Main entry point to our generator.
--
-- `Rib.run` handles CLI arguments, and takes three parameters here.
--
-- 1. Directory `a`, from which static files will be read.
-- 2. Directory `b`, under which target files will be generated.
-- 3. Shake build action to run.
--
-- In the shake build 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|a|] [reldir|b|] $ do
  -- Copy over the static files
  Rib.buildStaticFiles [[relfile|static/**|]]
  -- Build individual markdown files, generating .html for each.
  --
  -- NOTE: We use TypeApplications to specify the type of the `doc` type
  -- variable, as used in the `Markup doc` constraint in the functions below.
  -- There are currently two possible values: `MMark` (if you choose to use the
  -- `mmark` parser) and `Pandoc` (if using pandoc).
  posts <- Rib.buildHtmlMulti @MMark [relfile|*.md|] (renderPage . Page_Doc)
  -- Build an index.html linking to the aforementioned files.
  Rib.buildHtml [relfile|index.html|]
    $ renderPage
    $ Page_Index posts
  where
    -- Define your site HTML here
    renderPage :: Markup doc => Page doc -> Html ()
    renderPage page = with html_ [lang_ "en"] $ do
      head_ $ do
        meta_ [httpEquiv_ "Content-Type", content_ "text/html; charset=utf-8"]
        title_ $ case page of
          Page_Index _ -> "My website!"
          Page_Doc doc -> toHtml $ title $ Rib.getDocumentMeta doc
        style_ [type_ "text/css"] $ Clay.render pageStyle
      body_
        $ with div_ [id_ "thesite"]
        $ do
          -- Main content
          with a_ [href_ "/"] "Back to Home"
          hr_ []
          case page of
            Page_Index docs ->
              div_ $ forM_ docs $ \doc -> li_ $ do
                let meta = Rib.getDocumentMeta doc
                b_ $ with a_ [href_ (Rib.getDocumentUrl doc)] $ toHtml $ title meta
                case description meta of
                  Just s -> em_ $ small_ $ toHtml s
                  Nothing -> mempty
            Page_Doc doc ->
              with article_ [class_ "post"] $ do
                h1_ $ toHtml $ title $ Rib.getDocumentMeta doc
                Rib.renderDoc doc
    -- Define your site CSS here
    pageStyle :: Css
    pageStyle = div # "#thesite" ? do
      marginLeft $ pct 20
      marginTop $ em 4
      "h1" ? do
        fontSize $ em 2.3

(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.

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/