filterIndexed.js

import { addIndex, filter } from 'ramda';

/**
 * {@link http://ramdajs.com/docs/#filter|R.filter} function that more closely resembles `Array.prototype.filter`.
 * It takes two new parameters to its callback function: the current index, and the entire list.
 *
 * `filterIndexed` implementation is simple: `
 *  const filterIndexed = R.addIndex(R.filter);
 * `
 *
 * @func filterIndexed
 * @memberOf RA
 * @since {@link https://char0n.github.io/ramda-adjunct/2.31.0|v2.31.0}
 * @category List
 * @typedef Idx = Number
 * @sig Filterable f => ((a, Idx, f a) -> Boolean) -> f a -> f a
 * @param {Function} pred The predicate function
 * @param {Array} list The collection to filter
 * @return {Array} Filterable
 * @see {@link http://ramdajs.com/docs/#addIndex|R.addIndex}, {@link http://ramdajs.com/docs/#filter|R.filter}
 * @example
 *
 * const isValueGtIndex = (val, idx) => val > idx;
 * RA.filterIndexed(isValueGtIndex, [5, 4, 3, 2, 1, 0]); //=> [5, 4, 3]
 */
const filterIndexed = addIndex(filter);

export default filterIndexed;