let random_state = Random.State.make_self_init

type t = string
let compare = String.compare
let nil = ""

let short ?(len) id =
	let id_len = String.length id in
	let l = match len with Some l -> l | None -> if id_len = 36 then 8 else 6 in
	String.sub id 0 (min l id_len)

let generate ?(len=6) ?(seed=random_state ()) () =
	let b32 i = char_of_int @@
		if i < 10 then i+48 else
		if i < 18 then i+87 else
		if i < 20 then i+88 else
		if i < 22 then i+89 else
		if i < 27 then i+90 else
		if i < 32 then i+91 else
		(invalid_arg ("id.char" ^ string_of_int i)) in
	let c _ = b32 (Random.State.int seed 31) in
	String.init len c