Demo Templates with Data Sort

datasort version = V1 | V2

datatype printer (v:version) = PrinterV1 (V1) | PrinterV2 (V2) 
typedef printer = [v:version] printer (v)

extern fun {v:version} hello (): void
implement hello<V1> () = println! "hello v1"
implement hello<V2> () = println! "hello v2"

extern fun {v:version} world (printer v): void
implement world<V1> (printer) = println! "world v1"
implement world<V2> (printer) = println! "world v2"

extern fun {v:version} foo (printer v): void
implement {v} foo (printer) = 
    case+ printer of 
    | PrinterV1 () => println! "foo v1"
    | PrinterV2 () => println! "foo v2"
    
extern fun bar (printer): void
implement bar (printer) = let 
    // val [v:version] p = printer: [v:version] printer (v)
in 
   foo (printer)
end

implement main0 () = let 
in
    hello<V1> ();
    hello<V2> ();
    world (PrinterV1);
    world (PrinterV2);
    foo (PrinterV1);
    foo (PrinterV2);
    bar (PrinterV1);
    bar (PrinterV2);
end