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)
"481a9e44-ffa5-466f-a0b3-201c3a9a604e"
> (uuid-generate)
"3b0e8dd6-bded-4a47-b0b3-32833b65a0ea"

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)
"dddf7e02-b449-4cb5-bf59-a116a4258871"
> (uuid-generate/random)
"98ca7790-487e-4c51-9f5b-d7fd4662649e"

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)
"a3f16b5a-59a3-11f1-83c2-ad8c3ebb189a"
> (uuid-generate/time)
"a3f17eba-59a3-11f1-83c2-ad8c3ebb189a"