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)
"947bead9-0b42-417d-8196-07c0614733fc"
> (uuid-generate)
"4eb02375-c51b-482d-a7c9-510ea040ecb2"

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)
"91db6824-7d87-42a0-877e-273963faa79d"
> (uuid-generate/random)
"5105a501-c64d-4f63-975a-30001052a294"

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)
"1db39dac-de72-11f1-a2f4-810efbce9eaa"
> (uuid-generate/time)
"1db3fc02-de72-11f1-a2f4-810efbce9eaa"