Racket

libuuid🔗ℹ

Interface to the libuuid library usable to generate high-quality UUIDs.

package: libuuid

procedure
(uuid-generate) → string?

Generate new universally unique identifier using /dev/urandom, if available. If it is not available, use current time, local ethernet MAC address and random data from a pseudo-random generator.

Examples:

> (uuid-generate)
"9c8c43cf-ed0c-4f66-a614-26a57c5ea37b"
> (uuid-generate)
"3f4267a0-148a-4141-843a-d73104c00f26"

procedure
(uuid-generate/random) → string?

When /dev/urandom is available, same as uuid-generate, but fails back to a pseudo-random generator only.

Can be used to prevent any chance of host’s MAC address leaking, at the cost of slightly higher chance of generating non-unique identifiers if the worst-case situation arises on multiple hosts.

Examples:

> (uuid-generate/random)
"4b9108fb-7500-4b12-a9d6-ab4a5094549e"
> (uuid-generate/random)
"84343c4c-8959-43c6-8e3e-f5a081515eb2"

procedure
(uuid-generate/time) → string?

Same as uuid-generate when the /dev/urandom is missing.

Could potentially produce non-uniqueue identifiers if used concurrently so if you do not absolutely need sequential identifiers, stick with the generic (and safe) uuid-generate function above.

Examples:

> (uuid-generate/time)
"ed34d466-7503-11f1-a240-3bc0031be37c"
> (uuid-generate/time)
"ed34f05e-7503-11f1-a240-3bc0031be37c"