Module BatRandom

Pseudo-random number generators (PRNG).

This module extends Stdlib's Random module, go there for documentation on the rest of the functions and types.

@documents Random

Basic functions

val init : int -> unit

Initialize the 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 generator with a more-or-less random seed chosen in a system-dependent way.

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.

  • since 3.4.0 and OCaml 4.13.0
val int_in_range : min:int -> max:int -> int
val int32 : Stdlib.Int32.t -> Stdlib.Int32.t

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

val int32_in_range : min:int32 -> max:int32 -> int32
val nativeint : Stdlib.Nativeint.t -> Stdlib.Nativeint.t

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

val nativeint_in_range : min:nativeint -> max:nativeint -> nativeint
val int64 : Stdlib.Int64.t -> Stdlib.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 (inclusive) and bound (exclusive). If bound is negative, the result is negative or zero. If bound is 0, the result is 0.

val int64_in_range : min:int64 -> max:int64 -> int64
val bool : unit -> bool

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

val char : unit -> char

Return a random Latin-1 character.

val full_range_int : unit -> int

full_range_int () returns the maximum entropy possible in a single int: 31 bits on 32-bit platforms and 63 bits on 64-bit platforms. Intentionally gives different results on different platforms, so is not portable.

Enumerations of random values.

val enum_bits : unit -> int BatEnum.t
val enum_int : int -> int BatEnum.t
val enum_bool : unit -> bool BatEnum.t
val enum_float : float -> float BatEnum.t
val enum_int32 : Stdlib.Int32.t -> Stdlib.Int32.t BatEnum.t
val enum_int64 : Stdlib.Int64.t -> Stdlib.Int64.t BatEnum.t
val enum_nativeint : Stdlib.Nativeint.t -> Stdlib.Nativeint.t BatEnum.t
val enum_char : unit -> char BatEnum.t

Working with data structures.

val choice : 'a BatEnum.t -> 'a

choice e returns a randomly-chosen element of e.

  • raises Empty

    when applied to an empty enum. This function only works on finite enumerations with less than 230 elements.

val multi_choice : int -> 'a BatEnum.t -> 'a BatEnum.t

multi_choice n e returns an enumeration of n randomly-chosen elements of e.

val shuffle : 'a BatEnum.t -> 'a array

shuffle e returns a new array, containing the same set of elements as e, but in a random order.

Shuffling is implemented using the Fisher-Yates algorithm and works in O(n), where n is the number of elements of e.

This function only works on finite enumerations with less than 230 elements.

val bits32 : unit -> Stdlib.Int32.t

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

  • since 4.14.0
val bits64 : unit -> Stdlib.Int64.t

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

  • since 4.14.0
val nativebits : unit -> Stdlib.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.

  • since 4.14.0

Advanced functions

module State : sig ... end

Manipulate the current state of the random generator.

val get_state : unit -> State.t

Return the current state of the generator used by the basic functions.

val set_state : State.t -> unit

Set the state of the generator used by the basic functions.

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.

  • since 3.6.0 and OCaml 5.0.0
module Incubator : sig ... end