Reactive Programming with F# in London

If you’re a registered member of the F#unctional Londoners user group, then you maybe already know that I'll be visiting London on June 23 and I’ll be talking about Reactive programming with F#. If you're not a registered member and occasionally visit London, then you should definitely register. The user group is organized by Carolyn Miller and Phil Trelford (whom I met some time ago at Microsoft Research in Cambridge). Among others, previous speakers include Robert Pickering (who also presented some samples based on my F# and Accelerator series). Finally, another reason for joining the group is that it has a great name (as well as a logo)!

When, what & where?

• Tomas Petricek on Reactive Programming with F#
• Date & time: 23 June (Wednesday), 6:30 PM
• Location: The Skills Matter eXchange, 116-120 Goswell Road, London

By the way, I'll also have a free copy of my Real-World Functional Programming book to give away during the talk!

Reactive Programming with F#

I'm sure you're already convinced to come. Nevertheless, you may still want to know what I'm going to talk about. There are many areas where F# offers clear benefits such as parallel & concurrent programming. I believe that reactive programming is another great area for F#. In reactive programming, we face quite different problems than in other programming styles. We (as the authors of the application) can no longer specify what the application should do. Instead, the application needs to be able to handle many possible combinations of events. This aspect of programming is sometimes called inversion of control.

Reactive programming is important for programming user interfaces, especially today when user interfaces are becoming more interactive and more "fancy". To demonstrate this, I'm working on some nice Silverlight demos for the talk! However, it is also needed to handle other kinds of events such as completion of background task or message from other application. We'll look at the two essential techniques that F# provides for reactive programming:

• Declarative event combinators - one way of writing reactive applications is to specify the whole event processing declaratively by saying "what" should be done with occurrences of events. This is particularly useful when we need to encode simpler logic with a clear data-flow.
• Imperative using workflows - for more complicated interactions, we can use asynchronous workflows. This makes the code more explicit, but we get full control over the control-flow of the application. Even though this approach is more "imperative" it can be used for writing nicely composable functional code as well.

I'm looking forward to seeing you at the talk next week!