One of the benefits of implementing a language on top of .NET is that it enables developers using that language to get full access to the rich framework libraries provided with the .NET Framework.  

For a simple example of this in action, I could create a "HelloWPF.rb" text file and type in the following Ruby code below:

Figure 5

The above code uses the WPF UI framework to create a Window that hosts a StackPanel layout manager that initially contains just a button.  When the button is pressed, a new label control is created and added into the StackPanel (causing it to automatically be flowed in the Window). 

I can then run the above application using IronRuby by passing the "HelloWPF.rb" text file as an argument to rbx.exe:

Figure 6

When I run it I'll get a window with a WPF button (note above I added a nice DropShadowBitmapEffect to it in the code above):

Figure 7

And each time I press the button a new label will be added to the Window:

Figure 8

Not only does having the ability to use all of the .NET APIs provide a lot of power, but you'll notice in the code we wrote how it is possible to naturally integrate .NET APIs into other language syntaxes:

Figure 9

In the code snippet above I'm using the Ruby block language feature (similar to a Lambda expression with C# 3.0 and VB9) to implement a "Click" event handler on the WPF button.  Notice how within the block the standard Ruby naming patterns can be used when accessing any .NET API.  For example, instead of using the "FontSize" property on the WPF Label we are accessing it using "font_size" as the property accessor name. IronRuby automatically handles the naming conversion - enabling developers to program with a consistent naming pattern regardless of their language of choice.