F# Object Expressions http://msdn.microsoft.com/en-us/library/dd233237.aspx

I even commented about it a year or two ago of how I wanted to be able to create an anonymous object of an Interface. I want it implemented for C# also!  Maybe we can hope for it for C# 6.0.

type IFirst =
    abstract F : unit -> unit
    abstract G : unit -> unit


type ISecond =
    inherit IFirst
    abstract H : unit -> unit
    abstract J : unit -> unit


let implementer() = {
    new ISecond with
        member this.H() = ()
        member this.J() = ()

    interface IFirst with
        member this.F() = ()
        member this.G() = ()
}