Class RandomImpl

packages/effect/src/internal/random.ts:22–54

@internal

export const randomTag: Context.Tag<Random.Random, Random.Random> = Context.GenericTag("effect/Random")
/** @internal */
class RandomImpl implements Random.Random {
  readonly [RandomTypeId]: Random.RandomTypeId = RandomTypeId

  readonly PRNG: PCGRandom.PCGRandom

  constructor(readonly seed: number) {
    this.PRNG = new PCGRandom.PCGRandom(seed)
  }

  get next(): Effect.Effect<number> {
    return core.sync(() => this.PRNG.number())
  }

  get nextBoolean(): Effect.Effect<boolean> {
    return core.map(this.next, (n) => n > 0.5)
  }

  get nextInt(): Effect.Effect<number> {
    return core.sync(() => this.PRNG.integer(Number.MAX_SAFE_INTEGER))
  }

  nextRange(min: number, max: number): Effect.Effect<number> {
    return core.map(this.next, (n) => (max - min) * n + min)
  }

  nextIntBetween(min: number, max: number): Effect.Effect<number> {
    return core.sync(() => this.PRNG.integer(max - min) + min)
  }

  shuffle<A>(elements: Iterable<A>): Effect.Effect<Chunk.Chunk<A>> {
    return shuffleWith(elements, (n) => this.nextIntBetween(0, n))
  }
}

const shuffleWith = <A>(
  elements: Iterable<A>,