gistfile1.txt

$ cat Foo.pm
module Foo {
    my $_marshal_proto = my proto _marshal(|c) {*};

    $_marshal_proto.add_dispatchee(sub (Int $) { "Int" });

    sub get_marshal_proto is export is rw { $_marshal_proto }

    sub marshal(Any $x) is export {
        say $_marshal_proto($x)
    }
}
$ ./perl6-m -I. -MFoo -e'get_marshal_proto.add_dispatchee(sub (Str $) { "Str" }); marshal("foo")'
Str

Shiip it! 👍 ;-)