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)
"98a3d2b5-9cc6-46ca-a2fb-5e8300090f45"
> (uuid-generate)
"93bdfd78-cc79-40a8-a1a8-21577aa7fc19"

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)
"ca83cfa7-f3aa-4550-9242-2428140d1fa9"
> (uuid-generate/random)
"0bdf1da9-06db-46b3-9c7e-b283e73546ee"

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)
"0dec98b4-1074-11f1-9d20-59c2257112c0"
> (uuid-generate/time)
"0deca6e2-1074-11f1-9d20-59c2257112c0"