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)
"a583d1a6-c6c8-4b84-b777-15e4ea362470"
> (uuid-generate)
"64f9e769-7435-41cb-9969-9dce7ad67a87"

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)
"58d0e206-03cf-4c71-ba1e-e30adb7534a5"
> (uuid-generate/random)
"16b18205-b45f-46e9-9ba0-90ec41283337"

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)
"a0fa16da-8028-11f1-83d6-2d97ab9a4baf"
> (uuid-generate/time)
"a0fa2418-8028-11f1-83d6-2d97ab9a4baf"