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)
"99c95392-6ce7-4ab0-800d-50331f3d59bb"
> (uuid-generate)
"6fd927ba-cacc-41cf-9b9d-2e4b81fdb745"

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)
"855de201-f105-42b5-8733-3641e59e388f"
> (uuid-generate/random)
"6e1b4886-eb3c-4383-900f-b09bc8f91566"

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)
"1348f4fe-f2a3-11f0-b4cf-6d4749bd9487"
> (uuid-generate/time)
"1349025a-f2a3-11f0-b4cf-6d4749bd9487"