How can I interpolate a variable into a Perl 6 regex?

Question

Synopsis 05 mentions that Perl 6 doesn\'t interpolate variables into a regex, but you can associate an external variable with a pattern. The docs don\'t mention this feature

Answer 1

As an alternative to using a closure, you can of course build the regex via EVAL.

Besides these two arguably subpar solutions, I'm drawing a blank as well. Note that you can do more complex interpolations via the <{...}> syntax, eg

/ <{ BEGIN compute-string-once-at-compile-time }> /

but I don't see how that can be used to solve the problem...