Now you had me hoping for an implementation of fitting Needle behind the existing Pattern/Matcher API, and a compiler plugin that substitutes Pattern.compile accordingly wherever the inputs are known at compile time.
Author here: one thing I didn't mention in the post, but which is mentioned in the issues/readme on GitHub is that while I've been working on this for awhile, it's still a pretty new project in many ways. So what you're describing is interesting, but probably premature. The generated class files can still be very large, and the compiler itself has comments like "TODO: O(n^2)" that make throwing arbitrary input at it a dodgy idea.
Beyond those factors, there's the matter of just proving out that my testing is good enough, and I haven't missed edge cases.