effect/dist/cjs/internal/random.js

The missing standard library for TypeScript, for writing production-grade software.

"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.randomTag = exports.make = exports.RandomTypeId = void 0;
var Chunk = _interopRequireWildcard(require("../Chunk.js"));
var Context = _interopRequireWildcard(require("../Context.js"));
var _Function = require("../Function.js");
var Hash = _interopRequireWildcard(require("../Hash.js"));
var PCGRandom = _interopRequireWildcard(require("../Utils.js"));
var core = _interopRequireWildcard(require("./core.js"));
function _getRequireWildcardCache(e) { if ("function" != typeof WeakMap) return null; var r = new WeakMap(), t = new WeakMap(); return (_getRequireWildcardCache = function (e) { return e ? t : r; })(e); }
function _interopRequireWildcard(e, r) { if (!r && e && e.__esModule) return e; if (null === e || "object" != typeof e && "function" != typeof e) return { default: e }; var t = _getRequireWildcardCache(r); if (t && t.has(e)) return t.get(e); var n = { __proto__: null }, a = Object.defineProperty && Object.getOwnPropertyDescriptor; for (var u in e) if ("default" !== u && {}.hasOwnProperty.call(e, u)) { var i = a ? Object.getOwnPropertyDescriptor(e, u) : null; i && (i.get || i.set) ? Object.defineProperty(n, u, i) : n[u] = e[u]; } return n.default = e, t && t.set(e, n), n; }
/** @internal */
const RandomSymbolKey = "effect/Random";
/** @internal */
const RandomTypeId = exports.RandomTypeId = /*#__PURE__*/Symbol.for(RandomSymbolKey);
/** @internal */
const randomTag = exports.randomTag = /*#__PURE__*/Context.GenericTag("effect/Random");
/** @internal */
class RandomImpl {
  seed;
  [RandomTypeId] = RandomTypeId;
  PRNG;
  constructor(seed) {
    this.seed = seed;
    this.PRNG = new PCGRandom.PCGRandom(seed);
  }
  get next() {
    return core.sync(() => this.PRNG.number());
  }
  get nextBoolean() {
    return core.map(this.next, n => n > 0.5);
  }
  get nextInt() {
    return core.sync(() => this.PRNG.integer(Number.MAX_SAFE_INTEGER));
  }
  nextRange(min, max) {
    return core.map(this.next, n => (max - min) * n + min);
  }
  nextIntBetween(min, max) {
    return core.sync(() => this.PRNG.integer(max - min) + min);
  }
  shuffle(elements) {
    return shuffleWith(elements, n => this.nextIntBetween(0, n));
  }
}
const shuffleWith = (elements, nextIntBounded) => {
  return core.suspend(() => (0, _Function.pipe)(core.sync(() => Array.from(elements)), core.flatMap(buffer => {
    const numbers = [];
    for (let i = buffer.length; i >= 2; i = i - 1) {
      numbers.push(i);
    }
    return (0, _Function.pipe)(numbers, core.forEachSequentialDiscard(n => (0, _Function.pipe)(nextIntBounded(n), core.map(k => swap(buffer, n - 1, k)))), core.as(Chunk.fromIterable(buffer)));
  })));
};
const swap = (buffer, index1, index2) => {
  const tmp = buffer[index1];
  buffer[index1] = buffer[index2];
  buffer[index2] = tmp;
  return buffer;
};
const make = seed => new RandomImpl(Hash.hash(seed));
exports.make = make;
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