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)
"9b1af283-9085-4924-be66-ed2689e677e3"
> (uuid-generate)
"d5923195-a2fa-4e1b-9992-9719a636f57e"

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)
"d09ae4b9-2057-40e2-89bd-b620312eb66c"
> (uuid-generate/random)
"7e683028-aa47-4b22-b7c9-dbae468dab94"

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)
"0b43695c-6a07-11f1-a90a-5f90dd0697e3"
> (uuid-generate/time)
"0b4372b2-6a07-11f1-a90a-5f90dd0697e3"