If you take a look under the hood at the new System.Query name space you will see that the core of it is located in the “Sequence” class and this class bears an amazing resemblance to the F# List library located in the MLLib.dll. Okay you have to use your imagination a tiny bit, but if you consider that:
System.Collections.Generic.IEnumberable<T>()
Is really not that different from:
Microsoft.FSharp.List<A>
Then you start to see that:
val map: ('a -> 'b) -> 'a list -> 'b list // F# signature
public static List<B> map<A, B>(FastFunc<A, B> f, List<A> x); // C#...