Ooh, I like it. I actually had an idea written down somewhere about adding a UUID function. Granted, this is contrived, but I wonder if it's worth baking some flexibility in - e.g. make the function uuid4 or uuid(4) or something. Probably not worth it, but what do you think?

From the other angle - is returning a direct UUID object preferred? Should the expression at least return a string, and maybe we also add a toUuid(str) casting function? And similarly for scripting?

I can dig uuid4(), I think it's a good pattern. I thought about it but chose randomUUID because it matched with the underlying Java signature.

uuid(4) doesn't seem right; I can't think of any reason someone would want to parameterize the UUID version. Plus certain versions (specifically the non-random version 5 & 8) would need different signatures (like uuid5(name, namespace)).

My use case is for the string representation, but in my testing returning the UUID object seemed to give me the expected results everywhere I tried it (Perspective bindings, Vision bindings, expression tags) 🤷🏻‍♂️.

My thinking was that letting it get implicitly converted to a string was fine. You definitely know more than me about what's kosher for expression functions though, I don't have a strong preference.

Okay, cool. I think I'm convinced it's fine to hand back a 'true' UUID, probably more correct than anything else. Do you mind changing the expression and scripting functions to uuid4? That leaves us runway to implement our uuidv7, theoretically, which would otherwise be a bit confusing with "randomUUID" already in place.

Let's go uuid4 to save a character 😆

On the tests: Meh, there's not really anything to test (which I think is a good thing!) - we're just deferring to the JDK implementation, and there's no way to insert a testable RNG or anything into that, which I also think is good.

I'd honestly probably just test:

1. that the return value is a UUID instance
2. that the return value of two sequential calls is different, as you already have

I don't think there's anything else that would really add value.