Hac 2007 II

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Hac 07 II

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Hac 07 II: Haskell Hackathon

October 5-7, 2007

University of Freiburg, Freiburg, Germany

Photos and blogs



Hac 07 II - Freiburg, Germany. Group photo of hackers.


1. Clifford Beshers, thetallguy, (formerly Linspire, now SeeReason.org) 2. David Himmelstrup, Lemmih, HAppS Inc. 3. Conal Elliot, conal 4. Don Stewart, dons, Galois 5. Russel O'Connor, roconnor 6. Ben Lippmeier, benl23, ANU 7. Johan Tibell, tibbe, Google 8. Christophe Poucet, vincenz, IMEC 9. Tim Chevalier, Binkley, Portland State 10. Bjorn Bringert, Chalmers 11. Eric Kidd 12. Ivan Tarasov, ivant, Sun 13. Joachim nomeata Breitner 14. Ian Lynagh, Igloo 15. Thorkil Naur (thorkilnaur) 16. Thomas Schilling 17. Pepe Iborra 18. Conrad Barski 19. David Fox (formerly Linspire, now SeeReason.org) 20. Duncan Coutts, dcoutts, Oxford 21. Marcus Uneson 22. Phillip Heidegger, Freiburg 23. Ganesh, Heffalump, Credit Suisse 24. Lennart Kolmodin (kolmodin) 25. Jürgen Nicklisch, Jutaro 26. Alexey Yakushev Yakushev (mrchebas), Utrecht University



The 3rd Haskell Hackathon will be held over 3 days, October 5-7 2007, at the University of Freiburg, in conjunction with the Haskell Workshop and ICFP 2007. It is a coding festival, focusing on producing and improving Haskell libraries, tools and infrastructure.

To attend please register, and get ready to hack!

Note: that it is not necessary to register for ICFP, or any of the associated conferences, if you only want to go to the Hackathon. The Hackathon itself will be free, but you will have to pay for travel, accommodation and food.


If you will be attending add your name to the Registration page. Numbers may be limited, depending on availablity of space.


The Hackathon will take place at the same venue as the IFL workshop, at the Faculty of Applied Sciences of the University of Freiburg. The room is 02-016 in building 101.

You can reach the hackathon venue from the main train station by taking the "Breisgau S-Bahn" from "Freiburg - Hbf." to "FR Messe/Universitt". Here is a timetable (pdf). Please note that most but not all trains stop at the hackathon venue. Also, some trains only run Monday to Friday ("Montag - Freitag") or on Saturday ("Samstag").

Alternatively, you can walk from the city center to the hackathon (20 - 30 minutes). The map shows the exact route.


The Hackathon will be integrated with the university summer campus. This will give us all the infrastructure (room, Internet, etc) at minimal hassle. Note: There won't be any stationary PCs, so you should bring a laptop with you.

Local information

For local information (travel, accommodation etc) see the ICFP local info page.

Travel information page

Airport maps:


Hac 2007 II will take place on Fri 5 Oct to Sun 7 Oct. The following table shows the workshops and conferences held in Freiburg during the ICFP period:

Date Events
Thu 27 Sep IFL
Fri 28 Sep IFL
Sat 29 Sep IFL
Sun 30 Sep HW, Scheme
Mon 1 Oct ICFP
Tue 2 Oct ICFP
Wed 3 Oct ICFP
Thu 4 Oct CUFP, MM
Fri 5 Oct Hac 2007 II, Erlang, ML, PV
Sat 6 Oct Hac 2007 II
Sun 7 Oct Hac 2007 II

The Hackathon will, tentatively, be held from 10am to 6pm each day, with dinner after at local venues.


What to bring

  • A laptop
  • Wireless cards
  • Power adaptors if necessary
  • Ethernet cable
  • Mobile phone

Before you arrive

  • Pick out a couple of projects to work on and familiarise yourself with them
  • Install an up to date Haskell toolchain (ghc-6.6.1 and if you like a recent snapshot of ghc-6.8.0 also).

Projects to work on

Add ideas here for which you think hacking together as a group (rather than individually) would be beneficial.

Group projects

  • Building tests that give 100% code coverage for package base.
  • Lots of Cabal hacking still to be done
  • Bindings for <your favourite C library>
  • Haskell library for <your favourite task>
  • Ensure hackage is ready for ghc 6.8

Other things

  • Bit layer on Data.Binary 1.0
  • libxml
  • bytestring parsec
  • combine strictcheck and quickcheck once and for all
  • darcs hacking
  • aggressive inlining for mtl?
  • Data.ByteString.Sequence - a ropes-alike lib based on specialised finger trees
  • Data.ByteString.Rope, based on
  • SGIs ropes or new ocaml ropes
  • bit parsing layer for Data.Binary and a network protocol demo?
  • dons: HPC coverage for bytestring 1.0
  • pretty printer-based ncurses interface
  • integrate darcs-piegraph and darcs-graph
  • improve the performance of DiffArray using modern techniques OCaml impl.
    • vincenz: Note that even underneath the hood, the ocaml impl is using impurity to implement this (namely the modification of the array in Diff)
  • New hs-plugins on top of ghc-api. Conal
  • Fast general, pure-Haskell image synthesis (speed of Pan or Pajama but via ghc). Use Harpy or a new hs-plugins. Conal
  • TiddlyWiki-based code & documentation browser. Syntax-colored and all identifiers fully hyperlinked to sources. Thanks to TiddlyWiki, the browsing experience is fluid & self-organizing. Conal
  • Fix the Network.Socket API (at least to allow setSocketOption x RecvTimeOut and SendTimeOut)
  • Haskell WSGI (http://www.python.org/dev/peps/pep-0333/) equivalent with a reference server implementation.
  • UnicodeByteString layer (Text.UnicodeString maybe).
  • ByteString network API.
  • ByteString simple HTTP
  • Library to allow Haskell to communicate with Erlang processes using the Erlang message protocol.
  • A better curses rss client than snownews: support ^L resize signal, and parallel feed downloading.
  • benl23: Optimize new graph colouring register allocator.
  • jutaro: Information extraction for a Haskell IDE (Types,Completion,Navigation)
  • ivant: fix Functional MetaPost (figure out the problems of using it from LaTeX, add definitions for using it from ConTeXt, etc.)
  • Possibility to turn logging on/off in lambdabot per channel
  • Continuous build system, via as simple, general dependency tracking & execution formulated as an applicative functor and using DataDriven computation. No "make" info required (since inferred by construction). Applies uniformly to recompiling, re-executing, installing, compiler-recompiling, GUI specification and execution, etc. For compilation, it can give more precise (efficient) recompilation than language-specific tools (e.g., hmake and ghc --make) without being language-specific. Conal 13:51, 1 October 2007 (UTC)


The organisers for the Hackathon are:

The organisers can be contacted via:


The local organisers in Freiburg:

Courtesy of the Programming Languages Group at the University of Freiburg.

IRC channel

A Hackathon IRC channel has been set up. Visit:


on Freenode.

Previous Haskell hackathons

Related events

Hac 07 II is (unofficially) colocated with ICFP and other conferences:

IFL September 27-29
Haskell Workshop September 30
ICFP October 1-3
CUFP October 4


  • AJG: What can Galois do to help?
  • If there's anything that Credit Suisse can do to support the Hackathon, please let me know - [1]


The Freiburg background is available under the GNU Free Documentation License, from wikipedia.