Rand Module

The rand module provides random number generation, random selection, and shuffling. Import it with the rand. prefix.

Random Floats

rand.random()

Returns a random float in the half-open interval [0.0, 1.0).

rand.random()  // e.g. 0.6645600532184904

rand.uniform(a, b)

Returns a random float in the closed interval [a, b].

rand.uniform(1.0, 10.0)  // e.g. 7.234
rand.uniform(-1, 1)      // e.g. -0.412

Random Integers

rand.int()

Returns a random non-negative integer. Optionally accepts one or two arguments to constrain the range.

rand.int()        // random non-negative integer
rand.int(10)      // random integer in [0, 10)
rand.int(5, 15)   // random integer in [5, 15)

rand.randint(a, b)

Returns a random integer in the closed interval [a, b], inclusive of both endpoints.

rand.randint(1, 6)    // simulates a die roll: 1, 2, 3, 4, 5, or 6
rand.randint(0, 100)  // random integer from 0 to 100 inclusive

Distributions

rand.normal()

Returns a random value from a normal (Gaussian) distribution. Defaults to mean 0 and standard deviation 1. Optionally accepts mu and sigma parameters.

rand.normal()          // standard normal: mean=0, stddev=1
rand.normal(100, 15)   // mean=100, stddev=15

rand.exponential()

Returns a random value from an exponential distribution. Defaults to lambda = 1. Optionally accepts a lambda parameter.

rand.exponential()     // lambda=1
rand.exponential(0.5)  // lambda=0.5

Selection and Sampling

rand.choice(list)

Returns a single random element from a list.

let colors = ["red", "green", "blue"]
rand.choice(colors)  // e.g. "green"

rand.sample(list, k)

Returns a list of k unique random elements from the given list. The original list is not modified.

let numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
rand.sample(numbers, 3)  // e.g. [7, 2, 10]

rand.shuffle(list)

Shuffles a list in place, randomizing the order of its elements.

let deck = [1, 2, 3, 4, 5]
rand.shuffle(deck)
// deck is now in a random order, e.g. [3, 1, 5, 2, 4]

Random Bytes

rand.bytes(n)

Returns a list of n random integers in the range 0--255. Useful for generating tokens, nonces, or random identifiers.

rand.bytes(4)  // e.g. [182, 47, 233, 91]