Imported Upstream version 6.6.0.89

Former-commit-id: b39a328747c2f3414dc52e009fb6f0aa80ca2492

external/api-doc-tools/mdoc/mdoc.Test/mdoc.Test.FSharp/Interfaces.fs

@@ -0,0 +1,53 @@
+module Interfaces
+
+// You can implement one or more interfaces in a class type by using the interface keyword, 
+// the name of the interface, and the with keyword, followed by the interface member definitions, 
+// as shown in the following code.
+type IPrintable =
+   abstract member Print : unit -> unit
+   abstract member MyReadOnlyProperty :int
+
+type SomeClass1(x: int, y: float) =
+   interface IPrintable with
+      member this.Print() = printfn "%d %f" x y
+      member this.MyReadOnlyProperty = 10 
+
+// To call the interface method when you have an object of type SomeClass, 
+// you must upcast the object to the interface type, as shown in the following code.+
+let x1 = new SomeClass1(1, 2.0)
+(x1 :> IPrintable).Print()
+
+
+// An alternative is to declare a method on the object that upcasts and calls the interface method, 
+// as in the following example.
+type SomeClass2(x: int, y: float) =
+   member this.Print() = (this :> IPrintable).Print()
+   interface IPrintable with
+      member this.Print() = printfn "%d %f" x y
+      member this.MyReadOnlyProperty = 10 
+
+let x2 = new SomeClass2(1, 2.0)
+x2.Print()
+
+// Interface Inheritance
+type Interface0 = interface
+    abstract member Method1 : int -> int
+end
+
+// Interface Inheritance
+type Interface1 =
+    abstract member Method1 : int -> int
+
+type Interface2 =
+    abstract member Method2 : int -> int
+
+type Interface3 =
+    inherit Interface1
+    inherit Interface2
+    abstract member Method3 : int -> int
+
+type MyClass() =
+    interface Interface3 with
+        member this.Method1(n) = 2 * n
+        member this.Method2(n) = n + 100
+        member this.Method3(n) = n / 10