Hi, I'm impressed by Type Extension supported in F# which is similar to Extension Method supported in C# 3.0 when the target type and the member are placed within different namespaces/modules. But unfortunately, Type Extension cannot be recognized by C# 3.0. For the time being, it may be suggested to use explicit syntax to define Extension Method in F#, just like the following:

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#light

module Lib.Ext

#I @"C:\Program Files\Reference Assemblies\Microsoft\Framework\v3.5"
#r "System.Core.dll"
    
[<System.Runtime.CompilerServices.ExtensionAttribute>]
let PrintBook (b: Lib.Book) =
    printfn "%s by %s" b.Title b.Authors

where the Book was defined as follows:

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#light

namespace Lib

type Book =
    { Title: string;
      Authors: string;
      Price: double;
      Tags: string }

I compiled the project as a dll and referenced it from within a C# project. When I typed "Lib.Ext." in Visual C# 2008, I noticed that PrintBook has been recognized as an Extension Method in the IntelliSense dropdown list, just like other Extension Methods sit inside Enumerable class. But when I typed "b." (b was a Book object), I didn't find PrintBook method inside the IntelliSense dropdown list.

My questions are as follows:

1. Are there any ideas to work around the Extension Method issue, i.e. let C# 3.0 (or other languages) recognize it? Did I miss something important, or this is a known issue for the time being?
2. Will the underlying implementation of Type Extension be migrated to Extension Method? Or there will be two different ways for extending types?

Thanks in advance!