Channel 9 Forums - Coffeehouse - F# Object Expressions for C#

Coffeehouse - F# Object Expressions for C#

Soe Tun — Fri, 21 Dec 2012 06:23:32 GMT

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() = ()
}

Coffeehouse - F# Object Expressions for C#

felix9 — Fri, 21 Dec 2012 06:51:49 GMT

Don Syme will say: Just use F# !

Coffeehouse - F# Object Expressions for C#

Soe Tun — Fri, 21 Dec 2012 09:10:29 GMT

@felix9:Hehe I guess. I am using F# already on my own, but just about to start using it for my work projects.
Regardless, it would be nice to have it for the C# language also because it'd be neat.

Coffeehouse - F# Object Expressions for C#

Bent Rasmussen — Fri, 21 Dec 2012 17:39:36 GMT

Do you have a compelling use-case for it?

If I had to pick something from F# then Object Expressions would definitely not top the list. More like discriminated unions or the Scala equivalent. But even without those it's entirely possible to survive, using polymorphism and the visitor design pattern instead of pattern matching.