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)
"891496eb-2885-4f80-8d38-71f8efb3f871"
> (uuid-generate)
"f0f34e8e-c68c-47aa-a853-c5192a513547"

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)
"68969ea9-c690-4cf2-ac03-2a59fb656830"
> (uuid-generate/random)
"db580cb8-e953-421e-8d82-e1f944c1a6ad"

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)
"bc821b48-fe3f-11f0-99ff-d14590307630"
> (uuid-generate/time)
"bc8225ac-fe3f-11f0-99ff-d14590307630"