gistfile1.fs

// Based on http://www.nut-cracker.com.ar/index.php/overloading-in-f

type IVec<'T> =
    abstract member Add : 'T -> 'T
    abstract member Inv : unit -> 'T

type Vector2D = Vector2D of float * float with
    interface IVec<Vector2D> with
        member x.Add (Vector2D(b1, b2)) = match x with Vector2D(a1,a2) -> Vector2D(a1+b1, a2+b2)
        member x.Inv () = match x with Vector2D(a1, a2) -> Vector2D(-a1, -a2)

type Vector3D = Vector3D of float * float * float with
    interface IVec<Vector3D> with
        member x.Add (Vector3D(b1, b2, b3)) = match x with Vector3D(a1,a2,a3) -> Vector3D(a1+b1, a2+b2, a3+b3)
        member x.Inv () = match x with Vector3D(a1, a2, a3) -> Vector3D(-a1, -a2, -a3)
 
let addVec (x:IVec<'a>) y = x.Add(y)
let subVec (x:IVec<'a>) (y:IVec<'a>) = addVec x (y.Inv());;

(*
> addVec (Vector2D (1.,2.)) (Vector2D (3.,4.));;
val it : Vector2D = Vector2D (4.0,6.0)
> addVec (Vector2D (1.,2.)) (Vector3D (3.,4.,5.));;

  addVec (Vector2D (1.,2.)) (Vector3D (3.,4.,5.));;
  ---------------------------^^^^^^^^^^^^^^^^^^^

stdin(17,28): error FS0001: This expression was expected to have type
    Vector2D    
but here has type
    Vector3D    
> addVec (Vector3D (1.,2.,3.)) (Vector3D (3.,4.,5.));;
val it : Vector3D = Vector3D (4.0,6.0,8.0)
*)

Post moved to http://nut-cracker.azurewebsites.net/overloading-in-f