Possible to use Promise.in with infinite time?

You can actually pass Inf to Promise.in, like this:

await Promise.in(Inf);
say "never happens";

whenever Promise.new {

pretty much gives you a promise that will never be kept, so the associated code will never fire. Not sure why you would do that, though.

If you want a promise that is never fulfilled, simply running Promise.new gives you one.

Somebody could still call .keep on that promise, unless you obtain a vow to prevent that.