From HaskellWiki
< ZuriHac2010
Revision as of 16:12, 4 March 2010 by EricKow (talk | contribs) (darcs :-))

Jump to: navigation, search

Generic information

You can apply for an account and a project using the community server.

Once you have an account and/or a project, you upload a Darcs repository as follows. First, initialize your repository on the server:

 $ ssh community.haskell.org
 you@haskell:~$ cd /srv/code/yourproject
 you@haskell:/srv/code/yourproject$ darcs init

Then, log out and push your repository:

 $ darcs push community.haskell.org:/srv/code/yourproject


If you have a project that you want to work on at the Hackathon, please describe it here.

Since Hackathons are great for teamwork, consider joining one of the projects mentioned below. If you're interested in one of these projects, add your name to the list of hackers under that project.


The Darcs team will be at ZuriHac. We would be delighted for you to join in and do some hacking with us. To help you get started, we have a big list of ProbablyEasy bugs to chew on. See our sprint page for more details!

Need for speed

In 2006 the Python community had a NeedForSpeed sprint. Some Haskell libraries, like the containers library, could use some benchmarks (using e.g. [http://hackage.haskell.org/package/criterion Criterion) and hopefully some performance improvements.


The event library will hopefully replace GHC's I/O manager with a more scalable implementation, based on better data structures and more efficient system calls (e.g. epoll/kqueue).

The project is nearing completion, but more testing and benchmarking is needed. The code also needs to be merged into GHC.

Hackers: Johan Tibell

Data.Binary on continuations

The Data.Binary library provides blazing fast reading/writing of binary data. There are a few things I'd like to see improved, hopefully before inclusion in the Haskell Platform:

  • It's not possible to use the library on large inputs without resorting to lazy I/O. By changing the underlying implementation to use continuations and expose a continuations based API we can process large inputs without resorting to unsafe operations. This needs to be done while still offering good performance.
  • The library lacks error handling. The above implementation would naturally support communicating errors to the user. There are however other ways to achieve the same result.
  • The library currently includes two separate features in one package, low-level binary parsing of simple types (e.g. Ints and Words) and a data format (the Binary typeclass). Arguably the library should be split in two.
  • The binary data format should be documented and it should be clear which types are guaranteed to have the same encoding for the foreseeable future.

Hackers: Johan Tibell

Adaptable containers

Scala's collection library was completely overhauled in 2.8. The containers library is a bit dated. There are several things that could be done:

  • Write a new library based on associate data types, yielding performance improvements.
  • Write more tests and add some Criterion benchmarks.
  • Consolidate API naming, exported functions, etc.


Please list projects with which you are familiar. This way, people know whom to contact for more information or guidance on a particular project.

Name Projects
tibbe event, Hyena, and general networking/HTTP