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)
"05e5e980-7ba0-4e24-8fbf-aaf48d75cc73"
> (uuid-generate)
"f26f774b-e414-4982-b05b-3767e896facc"

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)
"6e3b520f-8b8e-4ab3-9473-1334fa360df1"
> (uuid-generate/random)
"a0c5c323-8bd0-4f02-a888-1d1328a07e47"

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)
"cb19a22c-1459-11f1-9596-f1e92b7a8821"
> (uuid-generate/time)
"cb19a9b6-1459-11f1-9596-f1e92b7a8821"