Ada for the C++ and Java Developer [pdf](learn.adacore.com)

    with Ada.Text_IO; use Ada.Text_IO;
    
    procedure Main is
       type Distance is record
          Value : Float;
       end record;
    
       type Area is record
          Value : Float;
       end record;
    
       function "*" (Left, Right : Distance) return Area is
       begin
          return (Value => Left.Value * Right.Value);
       end "*";
    
       D1 : constant Distance := (Value => 10.0);
    
       D2 : constant Distance := (Value => 20.0);
    
       -- D3 : constant Distance := D1 * D2;
       -- Does not compile. GNAT returns the following error:
       --   main.adb:21:33: expected type "Distance" defined at line 4
       --   main.adb:21:33: found type "Area" defined at line 8
    
       A : constant Area := D1 * D2;
    begin
       Put_Line ("Area A is " & Float'Image(A.Value));
    end Main;*

     type Distance is new Float;
     type Area is new Float;

   function "*" (Left, Right : Distance) return Area is
     temp : Distance;
   begin
     temp := Left * Right;
     return Area (temp);
   end "*";

     D1 : Distance := 2.0;
     D2 : Distance := 3.0;
     A  : Area;

  begin
     A  := D1 * D2; -- OK
     Put_Line(A'Image);
 end Main;

   function "*" (Left, Right : Distance) return Area is
   begin
      return Left * Right;
   end "*"; --   ^ Does not work
            --   raised STORAGE_ERROR : stack overflow or erroneous memory access

   function "*" (Left, Right : Distance) return Area is
   begin
      return Area (Left * Right);
   end "*"; --  ^ Does not work either, compiler gives me "ambiguous operand in conversion"

  function "*"(Left, Right : Distance) return Area