prng

🎲 A Pure Random Number Generator (PRNG) for Gleam

This package can help you generate any kind of random values you can think of. It can be useful in many different scenarios: when you need to simulate non-deterministic actions, like rolling a dice or flipping a coin; when you need to write property based tests; or to make fun interactive games where you can spawn randomly generated enemies!

To add this package to your Gleam project:

gleam add prng

And you can start generating random values:

import prng/random
import prng/seed

pub fn main() {
  // A generator describes which kind of random values to produce:
  let generator = random.int(0, 10)

  // One can take values out of a generator using the `step` function.
  // Using the same initial seed will always produce the same value!
  let #(value, _) = random.step(generator, seed.new(11))
  let #(other_value, _) = random.step(generator, seed.new(11))
  assert value == 10
  assert other_value == 10
}

The step function also produces a new seed you can use on successive calls to generate a new pseudo-random value each time you call it:

pub fn main() {
  let generator = random.int(0, 10)
  let #(value, next_seed) = random.step(generator, seed.new(11))
  let #(other_value, _) = random.step(generator, next_seed)
  assert value == 10
  assert other_value == 4
}

References

This package and its documentation are based on the awesome Elm implementation of Permuted Congruential Generators. They have great documentation full of clear and useful examples; if you are curious, give it a look and show Elm some love!

Contributing

If you think there’s any way to improve this package, or if you spot a bug don’t be afraid to open PRs, issues or requests of any kind! Any contribution is welcome 💜