Static duck typing

gistfile1.txt

let inline speak (a: ^a) = 
    let x = (^a : (member Name: string) (a))
    printfn "I'm %s" x
    let y = (^a : (member talk: unit -> string) (a))
    printfn "I say %s" y

type Duck = 
    { Name : string }
        
    member x.talk() = "quackity quack"

type Dog(name) =
    member x.Name = name
    member x.talk() = "arrrr"


let x = { Name = "Donald" }
let y = new Dog("Pluto")
speak x
speak y

System.Console.ReadKey() |> ignore