F# Webcast (I.) - Introducing functional concepts

Now that Visual Studio 2010 Beta 1 is out, it is finally a good time to take a look at one of the (in my opinion) most interesting new features in the new release - the F# language. F# existed for quite a long time now as Microsoft Research project, but is now becoming a real Microsoft product. Interestingly, F# is still available as a plugin for Visual Studio 2008, so if you want to try it you don't have to install the whole new beta of 2010.

There are already many resources for learning F# including my functional programming overview, which is a Manning Greenpaper for the book Functional Programming for the Real World that I'm writing with Jon Skeet and my four-part F# introduction. There are also some useful links on the official F# web site including some talk recordings. However, I haven't yet seen any good F# webcast focusing mainly on showing F# source code, starting from simple functional concepts to the real-world features like asynchronous workflows and object-oriented programming in F#, so I decided to create one.

So, here it is! It is my first webcast and I'll be grateful for any feedback, comments and ideas!

What's next?

This webcast is the first part of four that I'm planning. It follows the usual F# development process where you start with experimenting and writing an initial version of the solution interactively using the F# interactive tool. In the later phase of the process, we modify the code to make it parallel and asynchronous and finally, we can also encapsulate it into a standard .NET library that's usable from C#. The first part of the webcast introduces some basic functional ideas and F# concepts, but then we'll look at simple real-world example - we'll look how to download RSS feeds from the internet, process it in F# to find posts that are interesting for us and we'll use this F# library from C# web application. Here is a list of all webcasts in the series:

• Part I. - Introducing functional concepts
  The first part introduces functional programming principles such as immutability, recursion and functions that take other functions as parameter (higher order functions). This can all be demonstrated in C# 3.0, so we start with C# and then look how the same concepts look in F#. Finally, the first part also shows functions for working with lists in F#.
• Part II. - Using standard .NET libraries
  The second part demonstrates how we can use standard .NET libraries. It uses classes from System.Net and System.Xml to download content of a web page (RSS feed), load it into XML document and process it to find only posts that contain some specified keyword.
• Part III. - Downloading web pages asynchronously
  The third part shows how to make the code from the part II. better. It introduces F# asynchronous workflows that can be used for writing code that doesn't block a thread when waiting for the completion of some I/O request. This part also shows how to modify the code to download and process multiple feeds in parallel.
• Part IV. - Developing standard .NET libraries
  In the fourth part, we look how to encapsulate the functionality written in F# into classes. We'll finally create a project (rather than just use F# scripts) and we'll wrap the code we wrote into a .NET class. We'll also look how to compile the project into DLL and how to use it from a simple C# web application.

Downloads

• Source code from the WebCast (ZIP)
• Download the video (WMV format, 21MB)

• Microsoft Visual Studio 2010 First Look - Microsoft.Com
• Visual Studio 2010 Beta1 with F# is now available, plus matching F# CTP Update for VS2008 - Don Syme's WebLog
• F# May CTP for Visual Studio 2008 - Microsoft Downloads