λondon HUG

Thinking about Meeting Number Two

Well, the first meeting of the Haskell User Group was, I think, a great success. Simon’s talk was fascinating, as were the discussions in the pub afterwards.

However, I’d like to see if we can do better. Some of the feedback suggested that the talk went over some people’s heads, which is understandable since I think we had a number of Haskell newbies in the audience, and even a few who were merely Haskell-curious. I really would like the LHUG to be inclusive of those people, so I would hope that next time we can have a better mixture of introductory material along with some of the more advanced stuff.

Here’s my suggestion for next time. Rather than one marathon talk, lets have two short talks, perhaps just 20 to 30 minutes long. Ideally one of these would be more introductory while the other one is a little more advanced. After that I propose a debate on the subject:

“Why isn’t functional programming more widely used in industry?”

To get the ball rolling on the talks, I can offer to talk on the subject “XML Processing with HXT and Arrows”. Please have a think about whether there is anything you would like to talk about, and send in your suggestions. Hopefully you’ll come up with better ideas than mine, so I don’t have to stand up and speak.

You’ll notice on the sidebar of this site there is a poll about the frequency of HUG meetings. I know we did a show of hands during the first meeting, which indicated strong support for a monthly meeting, but I have since been persuaded that that might be overdoing it. The initial energy and excitement of a new user group can quickly dissipate, so let’s give everybody some time to contemplate the previous meeting before rushing into the next one each time. I think the talks and discussions will feel a lot fresher with a bi-monthly or quarterly meeting. Anyway, place your vote, or comment below, and we’ll go with whatever the majority decide.

Video of SPJ’s Talk is now Online

I have uploaded a video of Simon’s talk on Nested Data Parallelism to Google Video. Click on the thumbnail to watch. The slides are here in PowerPoint format.

HUG Update: Nested Data Parallelism in Haskell

The following is the abstract of the talk that will be given at the inaugural meeting of the London HUG:

Nested data parallelism in Haskell
Simon Peyton Jones, Microsoft Research

There are many approaches to exploiting multi-cores, but a particularly promising one is the “data-parallel” paradigm, because it combines massive parallelism (on both shared and distributed memory) with a simple, single-control-flow programming model.

Alas, data-parallel programming is usually restricted to “flat” data parallelism, which is good for implementers but bad for programmers. In particular, all the parallelism must appear at a single point, which excludes useful paradigms such as divide-and-conquer, and inhibits modular programming.

I’ll describe the “nested” data parallel programming model, first developed in the 90’s. It is great for programmers but much harder to implement; as a result, it’s virtually unknown in practice. We are working on fixing this, by building a high-performance implementation in Haskell. I’ll tell you how it works and give you some numbers.

After Simon’s talk, I would like to propose an open discussion, kicking off with each person sharing some background about their interest in Haskell and level of experience (the answer “no experience yet” will be absolutely acceptable — we welcome everybody from newbies to gurus). It would also be great to hear people’s ideas for what they would like to get from future HUG meetings and what format they should take.

Finally, for anybody so inclined, the nearby Slaughtered Lamb has been suggested as a suitable establishment for post-HUG refreshments. Lets hope nobody ends up like the lamb.