Активные шаблоны

open System 
 
type IPrint = interface
    abstract member print: unit -> unit
    end
 
[<AbstractClass>]
type figure() = 
    abstract member area: unit -> float
 
type rectangle(a: float, b: float) =
    inherit figure()
    member this.a1 = a
    member this.b1 = b
    override this.area() = this.a1*this.b1
    override Object.ToString() = "Ширина прямоугольника: "+Object.a1.ToString()+", высота прямоугольника: "+Object.b1.ToString()+", площадь: "+Object.area().ToString() 
    interface IPrint with
        member this.print() = printfn "%s" (this.ToString())
 
type square(a: float) =
    inherit rectangle(a, 3.14)
    override this.area() = this.a1*this.a1
    override Object.ToString() = "Сторона квадрата: "+Object.a1.ToString()+", площадь: "+Object.area().ToString()
    interface IPrint with
        member this.print() = printfn "%s" (this.ToString())
 
type cycle(a: float) = 
    inherit figure()
    member this.a1 = a
    override this.area() = 2.0*3.14*this.a1
    override Object.ToString() = "Радиус круга: "+Object.a1.ToString()+", площадь: "+Object.area().ToString()
    interface IPrint with
        member this.print() = printfn "%s" (this.ToString())
 
type M_figure(a : float, b : float) =
    member x.radius = a
    member x.height = b
    member x.width = a
    member x.sq = a
 
let (|Rectangle|) (x : M_figure) = (x.height, x.width)
let (|Square|) (x : M_figure) = (x.sq)
let (|Cycle|) (x : M_figure) = (x.radius)
 
let area a =
    match a with
        | Square(aa) -> aa*aa
        | Rectangle(aa, ab) -> aa*ab
        | Cycle(aa) -> aa*2.0*3.14
 
[<EntryPoint>]
let main argv =
 
    let rec1 = rectangle(2.0, 3.0)
    let rec12 = rec1 :> IPrint
    rec12.print()
    
    let sq1 = square(2.0)
    let sq12 = sq1 :> IPrint
    sq12.print()
 
    let cyc1 = cycle(2.0)
    let cyc12 = cyc1 :> IPrint
    cyc12.print()
 
 
 
 
 
    Console.ReadKey() |> ignore
    
    0