Skills Matter Functional Programming Exchange

I had a great time today at the Functional Programming Exchange organised by Robert Pickering and Skills Matter. Robert managed to grab some really interesting speakers who gave a nice snapshot of the current art and use of FP. The whole caboodle was hosted in Skills Matter’s new London offices and they did a magnificent job; plenty of free tea, cakes, sandwiches and pizza. Geek heaven :)

Here’s a rundown of the talks:

Sadek Drobi – Computation Abstraction.
I was late getting the train up from Brighton and arrived half way through the first talk, which was a pity because in many ways it set the scene for the whole day. Sadek showed how functional programming allows abstractions that are not available in imperative languages. I really liked the discussion on error handling and how you can easily create your own control structures with higher-order functions. What was very nice was that he used a variety of Functional languages for his demos.

Matthew Sackman – Supercharged Rabbit: Resource Management at High Speed in Erlang
I really enjoyed this talk. Matthew took us on a whirlwind tour of RabbitMQ, an AMQP based messaging system implemented in Erlang. Apparently it can scale to queues as large as your disk space without sacrificing performance. Sounds very impressive. It was cool to hear about why Erlang makes such an excellent tool for writing highly concurrent software. It was also interesting to hear what Matthew disliked about Erlang in comparison with Haskell. I liked this quote, “Rabbit isn’t really fast, it can only manage 25,000 messages per second” … compared with MSMQ that is fast.

Anton Schwaighofer – F# and Units-Of-Measure for Technical Computing
This was a talk that surprised me the most. F# is the functional language that I’ve made the biggest effort to learn and I thought I understood units-of-measure. To be honest, they hadn’t made a particular impression on me. I was very impressed after Anton’s talk. I really liked the way that the compiler understands how computation affects units. So for example, if you have a function that takes miles and hours as its arguments and returns the miles divided by the hours, the compiler knows that the output is miles per hour.

Ganesh Sittampalam – Functional Programming for Quantitative Modelling at Credit Suisse
Ganesh gave some very practical examples of how his group at CS use both Haskell and F#. Once again the recurring theme was that Haskell is really good for writing DSLs. Ganesh explained how they had written a DSL to create Excel spreadsheets and the challenges that involved. He also explained how they were using F# now as their core application development language.

Duncan Coutts – Strong Types and Pure Functions
I found Duncan’s talk the hardest to follow because of my almost complete ignorance of Haskell. Apparently Haskell allows you specify the side effects that a function is allowed to have in its type signature. By default Haskell is a side effect free language. That immutability or ‘pureness’ allows all kinds of optimisations and is one of the fundamentals of functional programming, but sometimes you have to have side effects. Any IO functions will fall into this category. What Haskell allows you to do is specify with a ‘Monad’ what side effects are allowed. I’m going to have to read a Haskell book.

Robert Pickering – Using Combinators to Tackle the HTML Rendering Problem
Robert showed us an F# DSL to generate HTML and Javascript. I guess it was more interesting from the DSL point of view than the HTML/Javascript generation. The DSL meme runs throughout FP and it’s instructive to see how trivial it is to write a simple DSL in F#. I just didn’t like the example. I have a fundamental distrust of tools that try to hide me from HTML and Javascript; I like HTML and Javascript. We’re only just recovering a back-to-basics approach from the WebForms train wreck so I’m a bit twitchy about this kind of thing.. back off Robert.. OK!