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)
"963fa221-0576-4796-a0fa-b84704e8d877"
> (uuid-generate)
"05e79828-c087-4495-8f89-5fb49c4979f8"

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)
"b2716d8f-cab1-4198-ae2c-aafa2342128d"
> (uuid-generate/random)
"52cd592b-37c8-4ef4-937f-4935f8f7b096"

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)
"41227252-42f2-11f1-8bf7-87efb2d6a38a"
> (uuid-generate/time)
"41228170-42f2-11f1-8bf7-87efb2d6a38a"