isSentinelValue.js

import { curryN } from 'ramda';

import isInteger32 from './isInteger32';

/**
 * Checks whether the passed value is {@link https://github.com/getify/You-Dont-Know-JS/blob/9959fc904d584bbf0b02cf41c192f74ff4238581/types-grammar/ch4.md#the-curious-case-of-the-|a sentinel value}.
 *
 * @func isSentinelValue
 * @memberOf RA
 * @since {@link https://char0n.github.io/ramda-adjunct/2.33.0|v2.33.0}
 * @category Type
 * @sig * -> Boolean
 * @param {*} val The value to test
 * @return {boolean}
 * @example
 *
 * RA.isSentinelValue(-1); //=> true
 *
 * RA.isSentinelValue('-1'); //=> false
 * RA.isSentinelValue(1); //=> false
 * RA.isSentinelValue([-1]); //=> false
 */
// eslint-disable-next-line no-bitwise
const isSentinelValue = curryN(1, (val) => isInteger32(val) && ~val === 0);

export default isSentinelValue;