package stdlib-random

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package stdlib-random
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Module Random5oSource

Pseudo-random number generators (PRNG).

Concurrency-safety with OCaml 5

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 Random5.split function and used with the functions from the Random5.State module.

Basic functions

Sourceval 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.

Sourceval full_init : int array -> unit

Same as Random5.init but takes more data as seed.

Sourceval 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).

Sourceval bits : unit -> int

Return 30 random bits in a nonnegative integer.

Sourceval int : int -> int

Random5.int bound returns a random integer between 0 (inclusive) and bound (exclusive). bound must be greater than 0 and less than 230.

Sourceval full_int : int -> int

Random5.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, Random5.full_int bound is equal to Random5.int bound. If bound is greater than 230 (on 64-bit systems or non-standard environments, such as JavaScript), Random5.full_int returns a value, where Random5.int raises Invalid_argument.

Sourceval int32 : Int32.t -> Int32.t

Random5.int32 bound returns a random integer between 0 (inclusive) and bound (exclusive). bound must be greater than 0.

Sourceval nativeint : Nativeint.t -> Nativeint.t

Random5.nativeint bound returns a random integer between 0 (inclusive) and bound (exclusive). bound must be greater than 0.

Sourceval int64 : Int64.t -> Int64.t

Random5.int64 bound returns a random integer between 0 (inclusive) and bound (exclusive). bound must be greater than 0.

Sourceval float : float -> float

Random5.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.

Sourceval bool : unit -> bool

Random5.bool () returns true or false with probability 0.5 each.

Sourceval bits32 : unit -> Int32.t

Random5.bits32 () returns 32 random bits as an integer between Int32.min_int and Int32.max_int.

Sourceval bits64 : unit -> Int64.t

Random5.bits64 () returns 64 random bits as an integer between Int64.min_int and Int64.max_int.

Sourceval nativebits : unit -> Nativeint.t

Random5.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.

Advanced functions

The functions from module 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.

Sourcemodule State : sig ... end
Sourceval get_state : unit -> State.t

Return the current state of the domain-local generator used by the basic functions.

Sourceval set_state : State.t -> unit

Set the state of the domain-local generator used by the basic functions.

Sourceval split : unit -> State.t

Draw a fresh PRNG state from the current state of the domain-local generator used by the default functions. See Random5.State.split.