var _curry3 = require('./internal/_curry3');
var _reduce = require('./internal/_reduce');


/**
 * Returns a single item by iterating through the list, successively calling
 * the iterator function and passing it an accumulator value and the current
 * value from the array, and then passing the result to the next call.
 *
 * The iterator function receives two values: *(acc, value)*. It may use
 * [`R.reduced`](#reduced) to shortcut the iteration.
 *
 * The arguments' order of [`reduceRight`](#reduceRight)'s iterator function
 * is *(value, acc)*.
 *
 * Note: `R.reduce` does not skip deleted or unassigned indices (sparse
 * arrays), unlike the native `Array.prototype.reduce` method. For more details
 * on this behavior, see:
 * https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/reduce#Description
 *
 * Dispatches to the `reduce` method of the third argument, if present. When
 * doing so, it is up to the user to handle the [`R.reduced`](#reduced)
 * shortcuting, as this is not implemented by `reduce`.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category List
 * @sig ((a, b) -> a) -> a -> [b] -> a
 * @param {Function} fn The iterator function. Receives two values, the accumulator and the
 *        current element from the array.
 * @param {*} acc The accumulator value.
 * @param {Array} list The list to iterate over.
 * @return {*} The final, accumulated value.
 * @see R.reduced, R.addIndex, R.reduceRight
 * @example
 *
 *      R.reduce(R.subtract, 0, [1, 2, 3, 4]) // => ((((0 - 1) - 2) - 3) - 4) = -10
 *                -               -10
 *               / \              / \
 *              -   4           -6   4
 *             / \              / \
 *            -   3   ==>     -3   3
 *           / \              / \
 *          -   2           -1   2
 *         / \              / \
 *        0   1            0   1
 *
 * @symb R.reduce(f, a, [b, c, d]) = f(f(f(a, b), c), d)
 */
module.exports = _curry3(_reduce);