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)
"989de091-c8b9-434f-8773-c994eb882c34"
> (uuid-generate)
"6b06183c-4eec-4808-b833-55e0019c3218"

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)
"e6c626ea-d34b-4c73-ae58-94d60ea0842f"
> (uuid-generate/random)
"85ef5ed7-8080-4108-9e14-b348b09f3990"

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)
"cbbd2c88-3977-11f1-9e0d-5d0e3048cbc6"
> (uuid-generate/time)
"cbbd5096-3977-11f1-9e0d-5d0e3048cbc6"