ocaml-ulid

ULIDs are

• 128-bit compatibility with UUID 1.21e+24 unique ULIDs per millisecond
• Lexicographically sortable!
• Canonically encoded as a 26 character string, as opposed to the 36 character UUID
• Uses Crockford's base32 for better efficiency and readability (5 bits per character)
• Case insensitive
• No special characters (URL safe)
• Monotonic sort order (correctly detects and handles the same millisecond)

See the full spec here.

This package uses nocrypto's fortuna RNG for the random part of the ULID, but a different generator can be passed in with the signature int -> int (to generate a random number between 0 and n-1).

Help is welcome!

Installation

ulid can be installed with opam:

opam install ulid

Usage

basic ulid generation:

let ulid = Ulid.ulid ();; (* something like 01D07HWDR77VCQ6CC8XSDC916T *)

passing in a seed time instead of current time (see spec for more details):

let ulid = Ulid.ulid ?seed_time:123 ();;

getting monotonic ulids:

let get_ulid = Ulid.monotonic_factory ();;
let ulid = get_ulid ();;

using a different PRNG:

let get_ulid = Ulid.ulid_factory ~prng:my_favorite_prng ();;
let ulid = get_ulid ();;

License

MIT