Update: I do not use this system anymore, but this article may still be helpful.
I had this « make yourself a decent website » task on my todo list for more than a year. As I am more and more interested in what I do, I decided it was time to begin to give back and share some stuff I like.
Also, the « I should totally write a blog post about that! » situation happened too many times repeatedly these last weeks.
I think I will mostly write about Computer Science/Programming, and projects I like and/or make. But who knows...
The first thing I want to write about is how I made this website/blog.
There are lots of static website generators[^1], but Hakyll is the best I tried. It is fast, while being highly customizable. And it can handle many cool stuff almost out-of-the-box, including:
- markdown (and many other formats, because it uses Pandoc)
- incremental build (you don't have to rebuild everything on every modification)
- CSS compression
- tags and metadata
- RSS/Atom feeds
Making a static website by hand can be painful. To avoid repeating code, people often use dynamic languages (such as PHP). But this sounds like a waste to me: on each request, the server has to compute the same operations over and over to serve the same page, just because the developer wants DRY[^2] code. This makes sense when you need to handle user inputs, but that is not always the case. For that kind of projects, Hakyll is a really nice tool.
You can find the source code here: https://github.com/dsferruzza/david.sferruzza.fr
Some little details
Two static website generators are never exactly the same (that's the point). So building one involves picking up some stuff from the example site, or from nice people, and developing the rest.
I will quickly show some of these features I picked up or developed.
I'm still a beginner, so if you have better solutions, please let me know!
Links in feed
As I said, Hakyll is able to generate RSS and Atom feeds[^3]. While generating a post's page, we will tell Hakyll to take a snapshot of the result, just after converting the post's markdown to HTML, and just before applying it to a template. This snapshot will then be put in the feed.
But what if a post contains a relative link?
Well, it will stay relative, and that's what we want for the post's page. But we don't want that for the feed, because feed readers won't be able to resolve it.
A solution would be to use the
xml:base[^4] attribute in a root element of the feed.
The feed rendering function let me think it would be possible to override the default feed templates.
But I don't know if it is possible yet, nor how to do it...
So I picked up another solution from Clément Delafargue's blog. When generating posts' pages, Hakyll will resolve relative links before taking a snapshot for the feed, and then transform them back so that they will be relative in the rendered page (but not in the feed).
I believe that the first solution would be cleaner, but the second works nicely.
When I update a blog post, I want the date of the update to appear in the blog's page, but also in the feed (using
Hakyll handles that with a
modificationTimeField[^5] you can add to your post's context.
But I don't really like the idea of the modification date only be kept on my file system.
I want to be able to clone my blog's Git repository, build it and get exactly the same result every time.
This would not be the case if I use a
modificationTimeField, because Git don't store files' modification date.
So I created a
updatedField, which is implemented exactly like
dateField except that it only tries to get the date from a
updated field in my content's metadata.
updatedField :: String -> String -> Context a updatedField key format = field key $ \i -> do time <- getUpdatedTime locale $ itemIdentifier i return $ formatTime locale format time where locale = defaultTimeLocale getUpdatedTime :: MonadMetadata m => TimeLocale -> Identifier -> m UTCTime getUpdatedTime locale id' = do metadata <- getMetadata id' let tryField k fmt = M.lookup k metadata >>= parseTime' fmt maybe empty' return $ msum $ [tryField "updated" fmt | fmt <- formats] where empty' = fail $ "getUpdatedTime: " ++ "could not parse time for " ++ show id' parseTime' = parseTime locale formats = [ "%a, %d %b %Y %H:%M:%S %Z" , "%Y-%m-%dT%H:%M:%S%Z" , "%Y-%m-%d %H:%M:%S%Z" , "%Y-%m-%d" , "%B %e, %Y %l:%M %p" , "%B %e, %Y" , "%b %d, %Y" ]
Now, if I want to indicate that I updated a post, I just need to add something like
updated: 2014-12-01 12:30:00+02:00 in the post's metadata.
It will be synced by Git :)
ISO 8601 dates
I wanted to use
<time>[^6] tags in my posts' pages.
<time> tags binds a machine-readable date to a human-readable date.
This means we need a machine-readable date.
I picked up a quite simple solution from Julien Tanguy's blog.
You just need to add a new
dateField to the post's context.
dateField would have a format argument like that:
When you install Hakyll following the official tutorial, you type
cabal install hakyll, which installs globally the latest version of Hakyll.
In a previous project, I had some troubles when I started to update this globally-installed Hakyll.
So I decided I will use a sandbox this time.
Sandboxes ( in cabal > 1.18 ) are self contained environments of Haskell packages.[^7]
My haskell's dependencies (including Hakyll) are written in a
Then it's easy:
cabal sandbox initto initialize the sandbox
cabal install --dependencies-onlyto install dependencies
It seems like, in a near future, Hakyll will generate the
.cabal file when doing a
Of course, it is not possible to make a comment system using Hakyll. But it is possible to integrate one.
I was lazy so I choose to use Disqus. As it includes a lot of stuff (Google Analytics, ~ 700 ko of data which is around 200% of this page's size without comments), I don't let it load itself automatically.
I made something quick and dirty to do so:
You should give Hakyll a try!
[^1]: Someone even made a website to list them [^2]: Don't Repeat Yourself [^3]: See the official tutorial [^4]: See https://developer.mozilla.org/en-US/docs/XML/xml:base [^5]: See http://jaspervdj.be/hakyll/reference/Hakyll-Web-Template-Context.html#v:modificationTimeField [^6]: Specification: http://www.w3.org/TR/html5/text-level-semantics.html#the-time-element [^7]: I took this quote from http://dev.stephendiehl.com/hask/ [^8]: According to https://github.com/jaspervdj/hakyll/issues/267