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)
"8d42133f-dcb2-4402-9071-7ab03504cff4"
> (uuid-generate)
"994d626e-7b71-4eb9-92b1-aa73a223458f"

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)
"bdf14908-af70-4e00-b2ed-76ee54132060"
> (uuid-generate/random)
"669b87b4-afef-4c3d-a1f2-5b61aba7f0f5"

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)
"e9136014-31a1-11f1-b12a-a5fc94760f76"
> (uuid-generate/time)
"e9136884-31a1-11f1-b12a-a5fc94760f76"