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)
"2db9ba46-e3ae-4bfb-91f1-935c58e6a69a"
> (uuid-generate)
"ff345111-27db-472d-9a96-fcbfa395fd55"

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)
"e1f368a8-540e-484b-93c7-4066310bf985"
> (uuid-generate/random)
"80a73c72-ba20-4827-9037-8181f967143a"

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)
"943077ce-0237-11f1-95af-776c98d7b1cd"
> (uuid-generate/time)
"94307dc8-0237-11f1-95af-776c98d7b1cd"