Interop of delegate style types between F# and other .Net languages is a pain point that results from a fundamental difference in how delegates are represented in the F# language. Typical .Net languages like C# see a delegate as taking 0 to N parameters and potentially returning a value. F# represents all exposed delegates as taking and returning a single value via the FSharpFunc<T,TResult> type. Multiple parameters are expressed by having the TResult type be yet another FSharpFunc<T,TResult>.

Multi-targeting is a feature introduced in Visual Studio 2008 which allows developers to use new versions of Visual Studio to target earlier versions of the .Net platform. It allowed users to target both the new 3.5 and 3.0 and the previous 2.0 profile with the same IDE. Visual Studio 2010 continues this trend by adding support for CLR 4.0 and even allows for further sub-targeting through several framework profiles.

One source of confusion I find myself clearing up a lot is the use of evaluating extension methods in the debugger windows. Users report evaluation as working sometimes but not others for the exact same piece of code. Such flaky behavior can only be the result of a poorly implemented feature or subtle user error. Right’

A couple of days ago I finished coding up a feature in our C++ code base, hit F5 and was met with a nasty memory corruption debugger dialog. After about an hour of investigation it appeared one of my types was living past the lifetime of it’s owning heap. I decided the next step was to debug on the heap functions to see where I went wrong. I opened up the file for the heap and almost immediately new what I had done wrong.

I just released an update to VsVim for Visual Studio 2010. This is available on the extension manager in Visual Studio or can be downloaded directly at the following link.