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)
"6388e787-e716-424e-aaa7-cc8c8c30f45d"
> (uuid-generate)
"2671a5f5-c8f0-4edd-bc5b-03cbf2084633"

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)
"96ed5a15-d0c4-4587-8017-9c1345833456"
> (uuid-generate/random)
"6f0ebcf2-e801-462a-ab42-a2c3b40fb42a"

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)
"ba3c5064-cf23-11f1-b15a-2b9cfb8c2029"
> (uuid-generate/time)
"ba3c726a-cf23-11f1-b15a-2b9cfb8c2029"