lfest: A Routing Party for LFE Web Apps

The Clojure community (in particular, James Reeves) has produced one of the best APIs I've seen for creating RESTful services, or any application using path dispatching (routing), really: Compojure.

I've been really missing this in LFE. Despite the fact that creating RESTful apps in LFE with YAWS is so simple it doesn't even need a framework, the routes can be a bit difficult to read, due to some of the destructuring that's done (e.g., URL paths).

Take the following route declaration from the yaws-rest-starter project:

Note that this example delegates additional routing to other functions, since all the routing in one function was pretty difficult to read. This, however, detracts from the overall readability in a different way: there's not one place to look to see what functions map to the complete URL-space for this service.

I wanted to be able to do something like what you can do in Clojure:

LFE is a Lisp with macros, so why not? Also, nox or mheise (I forget who) on the #erlang-lisp channel had previously noted all the lfe* projects (and these too), and suggested that someone create the inevitable "lfest" repo on Github.

Enter lfest. After a weekend of hacking and debugging some tiny macros, surprisingly little code now supports routes definitions like the following in LFE+YAWS web apps:

If you're curious to see what this actually expands to before getting compiled in a .beam file, you can view it here.

Bonus for LFE webdevs: this project also has a module of HTTP status codes, for easy re-use in other projects.

The recent work I've been doing with macros has really helped shape the section I've been planning to write in the LFE User Guide. I haven't wanted it to be yet another dry description of macros in a Lisp-2. Instead, my hope is to help jump-start people into how to think about macros, how to start writing them immediately (without years of study first), and how to debug them.

The trick, as with all complicated subjects, is how to remove the barrier to entry and get folks that necessary hands-on experience without dumbing-down the material. It's almost ready...

Also, it's Bay to Breakers today, and Ocean Beach is bumpin. The synchronicity is just eery. May you party just as hard with routes in LFE.

txSpore: Twisted Spore

I just had a delightful weekend of coding :-) I spent the past two days porting the Spore Python API to Twisted. You can now incorporate Spore data (from static XML as well as REST requests) into your non-blocking Python applications/games!

This was a pretty easy task, really. The API just makes HTTP requests with twisted.web.client.getPage. There was a little bit of work involved in creating object models for the XML, and some head-scratching for the error-catching deferToThread unit test I tried to write (it's still buggy... need to figure that one out). Everything else was pretty much cake.

In fact, it was so much fun to kick back and write some playful code that I might overhaul the sync Python code as well and incorporate both into txSpore.

Do be aware, however, that the code still has some big improvements coming. The first thing I want to hit is actually create a client object. Right now, the client module contains a series of functions (since state's not currently needed). However, I want to start doing some basic object caching in order to limit the number of requests made to spore.com and increase the response time. That's the big item for 0.0.2. Update: 0.0.2 is now released!

Next I'd like to create some more demo apps that show off the API usage better. Right now, there's one demo (a .tac file). All it does is ask for a user name, renders a user page, and then links to a user "Spore assets" page (that's the thumbnail image above).

One thing that might be fun to do is write a script that checks for the latest achievements and publishes them to various microblog/status sites with the Twisted PyngFM client :-)

There's a project page up on Launchpad for txSpore, and I've posted a notice and some updates to the Spore developer forums. It's also been published on PyPI.

Enjoy!