module Random: sig .. endPseudo-random number generators (PRNG).
With multiple domains, each domain has its own generator that evolves independently of the generators of other domains. When a domain is created, its generator is initialized by splitting the state of the generator associated with the parent domain.
In contrast, all threads within a domain share the same domain-local
generator. Independent generators can be created with the Random.split
function and used with the functions from the Random.State module.
val init : int -> unit
Initialize the domain-local generator, using the argument as a seed. The same seed will always yield the same sequence of numbers.
val full_init : int array -> unit
Same as Random.init but takes more data as seed.
val self_init : unit -> unit
Initialize the domain-local generator with a random seed chosen
in a system-dependent way. If /dev/urandom is available on the host
machine, it is used to provide a highly random initial seed. Otherwise, a
less random seed is computed from system parameters (current time, process
IDs, domain-local state).
val bits : unit -> int
Return 30 random bits in a nonnegative integer.
val int : int -> int
Random.int bound returns a random integer between 0 (inclusive)
and bound (exclusive). bound must be greater than 0 and less
than 230.
val full_int : int -> int
Random.full_int bound returns a random integer between 0 (inclusive)
and bound (exclusive). bound may be any positive integer.
If bound is less than 230, Random.full_int bound is equal to
Random.int bound. If bound is greater than 230 (on 64-bit systems
or non-standard environments, such as JavaScript), Random.full_int
returns a value, where Random.int raises Invalid_argument.
val int32 : Int32.t -> Int32.t
Random.int32 bound returns a random integer between 0 (inclusive)
and bound (exclusive). bound must be greater than 0.
val nativeint : Nativeint.t -> Nativeint.t
Random.nativeint bound returns a random integer between 0 (inclusive)
and bound (exclusive). bound must be greater than 0.
val int64 : Int64.t -> Int64.t
Random.int64 bound returns a random integer between 0 (inclusive)
and bound (exclusive). bound must be greater than 0.
val float : float -> float
Random.float bound returns a random floating-point number
between 0 and bound (inclusive). If bound is
negative, the result is negative or zero. If bound is 0,
the result is 0.
val bool : unit -> bool
Random.bool () returns true or false with probability 0.5 each.
val bits32 : unit -> Int32.t
Random.bits32 () returns 32 random bits as an integer between
Int32.min_int and Int32.max_int.
val bits64 : unit -> Int64.t
Random.bits64 () returns 64 random bits as an integer between
Int64.min_int and Int64.max_int.
val nativebits : unit -> Nativeint.t
Random.nativebits () returns 32 or 64 random bits (depending on
the bit width of the platform) as an integer between
Nativeint.min_int and Nativeint.max_int.
The functions from module Random.State manipulate the current state
of the random generator explicitly.
This allows using one or several deterministic PRNGs,
even in a multi-threaded program, without interference from
other parts of the program.
module State: sig .. end
val get_state : unit -> State.t
get_state() returns a fresh copy of the current state of the
domain-local generator (which is used by the basic functions).
val set_state : State.t -> unit
set_state s updates the current state of the domain-local
generator (which is used by the basic functions) by copying
the state s into it.
val split : unit -> State.t
Draw a fresh PRNG state from the current state of the domain-local
generator used by the default functions.
(The state of the domain-local generator is modified.)
See Random.State.split.