I am not an Ada expert, but I came up with this. Please notice that the idea here is not to have the compiler do proper dimensional analysis but simply to avoid the default operator overloading of "*" for the Distance type that also returns a Distance value.

Nothing very high-level, as we need to explicitly manipulate the single-component records, but it does the job.

    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;*