Initialize the generator, using the argument as a seed. The same seed will always yield the same sequence of numbers.

Same as Random4.init but takes more data as seed.

Initialize the 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).

Return 30 random bits in a nonnegative integer.

Random4.int bound returns a random integer between 0 (inclusive) and bound (exclusive). bound must be greater than 0 and less than 2³⁰.

• raises Invalid_argument

  if bound <= 0 or bound >= 2³⁰.

Random4.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 Random4.full_int bound yields identical output across systems with varying int sizes.

If bound is less than 2³⁰, then Random4.full_int bound is equal to Random4.int bound.

If bound is at least 2³⁰ (on 64-bit systems, or non-standard environments such as JavaScript), then Random4.full_int returns a value whereas Random4.int raises Stdlib.Invalid_argument.

• raises Invalid_argument

  if bound <= 0.

• since 4.13

Random4.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.

• raises Invalid_argument

  if min > max.

• since 5.2

Random4.int32 bound returns a random integer between 0 (inclusive) and bound (exclusive). bound must be greater than 0.

• raises Invalid_argument

  if bound <= 0.

Random4.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.

• raises Invalid_argument

  if min > max.

• since 5.2

Random4.nativeint bound returns a random integer between 0 (inclusive) and bound (exclusive). bound must be greater than 0.

• raises Invalid_argument

  if bound <= 0.

Random4.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.

• raises Invalid_argument

  if min > max.

• since 5.2

Random4.int64 bound returns a random integer between 0 (inclusive) and bound (exclusive). bound must be greater than 0.

• raises Invalid_argument

  if bound <= 0.

Random4.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.

• raises Invalid_argument

  if min > max.

• since 5.2

Random4.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.

Random4.bool () returns true or false with probability 0.5 each.

Random4.bits32 () returns 32 random bits as an integer between Int32.min_int and Int32.max_int.

Random4.bits64 () returns 64 random bits as an integer between Int64.min_int and Int64.max_int.

• since 4.14

Random4.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

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

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