module Random:sig..end
Pseudo-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 -> unitInitialize 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 -> unitSame as Random.init but takes more data as seed.
val self_init : unit -> unitInitialize 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 -> intReturn 30 random bits in a nonnegative integer.
val int : int -> intRandom.int bound returns a random integer between 0 (inclusive)
and bound (exclusive). bound must be greater than 0 and less
than 230.
Invalid_argument if bound <= 0 or bound >= 230.val full_int : int -> intRandom.full_int bound returns a random integer between 0 (inclusive)
and bound (exclusive). bound may be any positive integer.
If bound is less than 231,
then Random.full_int bound yields identical output
across systems with varying int sizes.
If bound is less than 230,
then Random.full_int bound is equal to Random.int bound.
If bound is at least 230
(on 64-bit systems, or non-standard environments such as JavaScript),
then Random.full_int returns a value
whereas Random.int raises Stdlib.Invalid_argument.
Invalid_argument if bound <= 0.val int_in_range : min:int -> max:int -> intRandom.int_in_range ~min ~max returns a random integer
between min (inclusive) and max (inclusive).
Both min and max are allowed to be negative;
min must be less than or equal to max.
If both bounds fit in 32-bit signed integers
(that is, if -231 <= min and max < 231),
then int_in_range yields identical output
across systems with varying int sizes.
Invalid_argument if min > max.val int32 : Stdlib.Int32.t -> Stdlib.Int32.tRandom.int32 bound returns a random integer between 0 (inclusive)
and bound (exclusive). bound must be greater than 0.
Invalid_argument if bound <= 0.val int32_in_range : min:int32 -> max:int32 -> int32Random.int32_in_range ~min ~max returns a random integer
between min (inclusive) and max (inclusive).
Both min and max are allowed to be negative;
min must be less than or equal to max.
Invalid_argument if min > max.val nativeint : Stdlib.Nativeint.t -> Stdlib.Nativeint.tRandom.nativeint bound returns a random integer between 0 (inclusive)
and bound (exclusive). bound must be greater than 0.
Invalid_argument if bound <= 0.val nativeint_in_range : min:nativeint -> max:nativeint -> nativeintRandom.nativeint_in_range ~min ~max returns a random integer
between min (inclusive) and max (inclusive).
Both min and max are allowed to be negative;
min must be less than or equal to max.
Invalid_argument if min > max.val int64 : Stdlib.Int64.t -> Stdlib.Int64.tRandom.int64 bound returns a random integer between 0 (inclusive)
and bound (exclusive). bound must be greater than 0.
Invalid_argument if bound <= 0.val int64_in_range : min:int64 -> max:int64 -> int64Random.int64_in_range ~min ~max returns a random integer
between min (inclusive) and max (inclusive).
Both min and max are allowed to be negative;
min must be less than or equal to max.
Invalid_argument if min > max.val float : float -> floatRandom.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 -> boolRandom.bool () returns true or false with probability 0.5 each.
val bits32 : unit -> Stdlib.Int32.tRandom.bits32 () returns 32 random bits as an integer between
Int32.min_int and Int32.max_int.
val bits64 : unit -> Stdlib.Int64.tRandom.bits64 () returns 64 random bits as an integer between
Int64.min_int and Int64.max_int.
val nativebits : unit -> Stdlib.Nativeint.tRandom.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.tget_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 -> unitset_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.tDraw 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.