package uuidm
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Authors
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Sources
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doc/uuidm/Uuidm/index.html
Module Uuidm
Universally unique identifiers (UUIDs).
Uuidm implements 128 bits universally unique identifiers version 3, 5 (name based with MD5, SHA-1 hashing) and 4 (random based) according to RFC 4122.
References
- P. Leach et al. A universally unique identifier (UUID) URN Namespace, 2005.
UUIDs
v3 ns n is a V3 UUID (named based with MD5 hashing) named by n and namespaced by ns.
v5 ns n is a V5 UUID (named based with SHA-1 hashing) named by n and namespaced by ns.
val v4 : bytes -> tv4 b is a V4 UUID (random based) that uses the first 16 bytes of b for randomness. Be aware that most of these 128 bits are seen literally in the result.
val v4_gen : Random.State.t -> unit -> tv4_gen seed is a function that generates random V4 UUIDs (random based) with the given seed.
Warning. Sequences of UUIDs generated using Stdlib.Random are suitably random but predictable by an observer. If that is an issue for you, use v4 with random bytes generated by a CSPRNG.
Informally deprecated
This interface is informally deprecated: it seems many people are using Uuidm.v `V4 in practice. For new code prefer one of the creation functions above.
type version = [ | `V3 of t * string(*Name based with MD5 hashing
*)| `V4(*Random based
*)| `V5 of t * string(*Name based with SHA-1 hasing
*)
]The type for UUID versions and generation parameters.
`V3and`V5specify a namespace and a name for the generation.`V4is random based with a private state seeded withStdlib.Random.State.make_self_init. Usev4_gento specify your own seed. Usev4to specify your own randomness.Warning. The sequence resulting from repeatedly calling
v `V4is random but predictable seev4_gen.
Constants
val nil : tnil is the nil UUID.
val ns_dns : tns_dns is the DNS namespace UUID.
val ns_url : tns_url is the URL namespace UUID.
val ns_oid : tns_oid is the ISO OID namespace UUID.
val ns_X500 : tns_dn is the X.500 DN namespace UUID.
Comparing
Standard binary format
This is the binary format mandated by RFC 4122.
val of_bytes : ?pos:int -> string -> t optionof_bytes pos s is the UUID represented by the 16 bytes starting at pos (defaults to 0) in s. The result is None if the string is not long enough.
val to_bytes : t -> stringto_bytes u is u as a 16 bytes long string.
Mixed-endian binary format
This is the binary format in which the three first fields of UUIDs (which are oblivious to this module) are read and written in little-endian. This corresponds to how UEFI or Microsoft formats UUIDs.
val of_mixed_endian_bytes : ?pos:int -> string -> t optionof_mixed_endian_bytes is like of_bytes but decodes the mixed endian serialization.
val to_mixed_endian_bytes : t -> stringto_mixed_endian_bytes is like to_bytes but encodes the mixed endian serialization.
US-ASCII format
val of_string : ?pos:int -> string -> t optionof_string pos s converts the substring of s starting at pos (defaults to 0) of the form "XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX" where X is a lower or upper case hexadecimal number to an UUID. The result is None if a parse error occurs.
val to_string : ?upper:bool -> t -> stringto_string u is u as a string of the form "XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX" where X is a lower (or upper if upper is true) case hexadecimal number.
Pretty-printing
val pp : Format.formatter -> t -> unitpp ppf u formats a representation based on to_string of u on ppf.
val pp_string : ?upper:bool -> Format.formatter -> t -> unitpp_string ?upper ppf u formats u on ppf like to_string would do.