Type-safe, K-sortable, globally unique identifier inspired by Stripe IDs

Yep. The whole point is that you /never/ assign ids that begin with "user" to types that are not users. Because of that, you can be sure nobody can accidentally copy an id that begins with "user" when meaning to address a different type and get back a result other than "not found".

Example:

I have userId=4 and userId=2. Suppose a user can have multiple bank accounts and userId=4 has accountId=5 and accountId=6 and a defaultAccound accountId=5. userId=2 has an account, accountId=7; I want to send userId=4 some money so I use the function `sendUserMoneyFromAccount(to: int, from: int)`. This is a bad interface but these things exist in the wild a lot. I could accidentally assume that because I want to send userId=4 the money to their default account that I would call it using `sendUserMoneyFromAccount(4, 7)` and that would work, but if under the hood it wants 2 accountIds, I've just sent accountId=4 money rather than userId=4's defaultAccount, accountId=5.

With prefixed ids that indicate type, a function that assumes type differently from the one supplied will not accidentally succeed.

In addition, humans who copy ids will be less likely to mistake them. This is just an ergonomic/human centric typing.

So you don't have to create an additional index to scan them in a somewhat sensible order. createdAt just happens to be a naturally decent scan order.

The F word has a U in it. Sure you could just say FVCK

While this isn't the worst area I see this in, there does seem to be a tendency in the UUID space to speak as if one use case stands for all and therefore there is a best UUID format.

The reality is that it is just like any other engineering situation. Sit down, write down your requirements, and see what, if anything, solves it.

Reading about the advantages of various formats is very helpful in helping you skip learning about certain things the hard way and use somebody else's experience of learning them the hard way instead. From that point of view I recommend at least glancing through them all. Sortability and time-based locality is one that you may not naturally think about, and if you need it, you will appreciate not learning that the hard way four years into a project after you threw that data away and then realizing you needed it. And some UUID formats actually managed to introduce small security issues into themselves (thinking MAC address leak from UUID v1 here), nice to avoid those too.

If you have a use case where there's an existing solution then, hey, great, go ahead and use it. Maybe if anyone ever needs that but in another language they can pull a library there too.

But if not, don't sweat it. The biggest use of UUIDs I personally have I specified as "just send me a unique string, use a UUID library of your choice if it makes you feel better". I think I've got a unique format per source of data in this system and it's fine. I don't have volume problems, it's tens of thousands of things per day. I don't have any need to sort on the UUID, they're not really the "identifier", they're just a unique token generated for a particular message by the originator of the message so we can detect duplicate arrivals downstream in a heterogenous system where I can't just defer that task to the queue itself since we have multiple. I don't even need them to be globally unique, I just need them unique within a rather small shard, and in principle I wouldn't even mind if they get repeated after a certain amount of time (though I left the system enforcing across all time anyhow for simplicity). In this particular case, I do indeed generate my own UUIDs for the stuff I'm originating by just grabbing some stuff from /dev/urandom and encoding it base64, with a size selected such that base64 doesn't end the encoding with ==. Even that's just for aesthetic's sake rather than any actual problem it would cause.