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5.18  Module Random

Pseudo-random number generator (PRNG).

val init : !random int -{!random ||}-> unit
Initialize the generator, using the argument as a seed. The same seed will always yield the same sequence of numbers.

val full_init : ([< !random] int, !random) array -{!random ||}-> unit
Same as Random.init but takes more data as seed.

val self_init : unit -{!random ||}-> unit
Initialize the generator with a more-or-less random seed chosen in a system-dependent way.

val bits : unit -{!random ||}-> !random int
Return 30 random bits in a nonnegative integer.

val int : 'a int -{!random ||}-> 'a int
          with !random < 'a bound returns a random integer between 0 (inclusive) and bound (exclusive). bound must be more than 0 and less than 230.

val float : 'a float -{!random ||}-> 'a float
            with !random < 'a
Random.float bound returns a random floating-point number between 0 (inclusive) and bound (exclusive). If bound is negative, the result is negative. If bound is 0, the result is 0.

val bool : unit -{!random ||}-> !random bool
Random.bool () returns true or false with probability 0.5 each.

type (='a:level, #'b:level) state
Values of this type are used to store the current state of the generator.

val get_state : unit -> (!random, !random) state
Returns the current state of the generator. This is useful for checkpointing computations that use the PRNG.

val set_state : ([< !random], !random) state -{!random ||}-> unit
Resets the state of the generator to some previous state returned by Random.get_state.

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