6.90. kink/random/RNG

Random number generators.

6.90.1. type rng

Abstract type of random number generator.

6.90.1.1. Rng.gen_int(Upper_bound)

`gen_int` produces a random int num in the range [0, Upper_bound).

Preconditions:

• `Upper_bound` must be an int num

• `Upper_bound` must be greater than or equal to 1

Every int nums in the range should be produced with approximately equal probability.

Example:

:PRNG.require_from('kink/random/')

:Rng <- PRNG.from_seed(42)
:Nums <- 10.times.map{ Rng.gen_int(3) }.vec
stdout.print_line(Nums.repr)
# => [2 0 2 2 1 0 2 1 2 2]

6.90.1.2. Rng.gen_bin(Size)

`gen_bin` produces a bin of the `Size` bits of which is randomly determined.

Preconditions:

• `Size` must be a non-negative int num

Probability of `1` bits and `0` bits should be approximately equal.

Example:

:PRNG.require_from('kink/random/')

:Rng <- PRNG.from_seed(42)
stdout.print_line(Rng.gen_bin(10).repr)
# => BIN.of(0x16 0x22 0xad 0x5f 0xe9 0xb6 0x94 0x4d 0x98 0xb1)

6.90.1.3. Rng.gen_bool

`gen_bool` produces a random bool.

Probability of true and false should be approximately equal.

Example:

:PRNG.require_from('kink/random/')

:Rng <- PRNG.from_seed(42)
:Bools <- 10.times.map{ Rng.gen_bool }.vec
stdout.print_line(Bools.repr)
# => [false true true false true true false false false true]

6.90.2. RNG.is?(Val)

`is?` returns whether `Val` is an rng val.