allEqual.js

import { pipe, uniq } from 'ramda';
import curry1 from 'ramda/src/internal/_curry1';

import lengthLte from './lengthLte';

// Original idea for this function was conceived by https://github.com/jackmellis
// in https://github.com/char0n/ramda-adjunct/pull/513.

/**
 * Returns true if all items in the list are equivalent using `R.equals` for equality comparisons.
 *
 * @func allEqual
 * @memberOf RA
 * @since {@link https://char0n.github.io/ramda-adjunct/2.9.0|v2.9.0}
 * @category List
 * @sig [a] -> Boolean
 * @param {Array} list The list of values
 * @return {boolean}
 * @see {@link https://ramdajs.com/docs/#equals|equals}
 * @example
 *
 * RA.allEqual([ 1, 2, 3, 4 ]); //=> false
 * RA.allEqual([ 1, 1, 1, 1 ]); //=> true
 * RA.allEqual([]); //=> true
 *
 */
const allEqual = curry1(
  pipe(
    uniq,
    lengthLte(1)
  )
);

export default allEqual;