Thanks Toby. It probably can't be accomplished with a type. With a JSON Schema you can say about an object (Dict) that it must contain one of a list of (named) keys each with their own type. You could require either a phone number or an email address, for example. So something like:

my $check = compile(Dict[
    foo   => Str,
    oneOf => [
        baz => Int,
        qux => Str,
    ],
]);
[download]

Something like this:

my $type = Dict->of(
  foo => Str,
  baz => Optional[Int],
  qux => Optional[Str],
)->where(q{ exists $_->{baz} or exists $_->{qux} });

if ( $type->check( \%somehash ) ) {
  say "matched";
}
[download]

Also, might be worth looking into JSON-Schema-AsType.

Hire me at Toby Ink Ltd or Join my OnlyFans