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)
"cf6f1a59-3b44-4f00-9a1f-9282f45e03b6"
> (uuid-generate)
"f40f90d6-905f-4102-8645-ec4091e47802"

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)
"1019fa53-0b10-4b2b-97e8-ba1c4d6b4de9"
> (uuid-generate/random)
"c8fba29e-e145-4948-8ac2-fb3775a78859"

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)
"953691d0-3536-11f1-87f6-1b39e8f20412"
> (uuid-generate/time)
"9536b160-3536-11f1-87f6-1b39e8f20412"