source: node_modules/ramda/es/reduce.js

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1import _curry3 from "./internal/_curry3.js";
2import _xReduce from "./internal/_xReduce.js";
3import _xwrap from "./internal/_xwrap.js";
4/**
5 * Returns a single item by iterating through the list, successively calling
6 * the iterator function and passing it an accumulator value and the current
7 * value from the array, and then passing the result to the next call.
8 *
9 * The iterator function receives two values: *(acc, value)*. It may use
10 * [`R.reduced`](#reduced) to shortcut the iteration.
11 *
12 * The arguments' order of [`reduceRight`](#reduceRight)'s iterator function
13 * is *(value, acc)*.
14 *
15 * Note: `R.reduce` does not skip deleted or unassigned indices (sparse
16 * arrays), unlike the native `Array.prototype.reduce` method. For more details
17 * on this behavior, see:
18 * https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/reduce#Description
19 *
20 * Be cautious of mutating and returning the accumulator. If you reuse it across
21 * invocations, it will continue to accumulate onto the same value. The general
22 * recommendation is to always return a new value. If you can't do so for
23 * performance reasons, then be sure to reinitialize the accumulator on each
24 * invocation.
25 *
26 * Dispatches to the `reduce` method of the third argument, if present. When
27 * doing so, it is up to the user to handle the [`R.reduced`](#reduced)
28 * shortcuting, as this is not implemented by `reduce`.
29 *
30 * @func
31 * @memberOf R
32 * @since v0.1.0
33 * @category List
34 * @sig ((a, b) -> a) -> a -> [b] -> a
35 * @param {Function} fn The iterator function. Receives two values, the accumulator and the
36 * current element from the array.
37 * @param {*} acc The accumulator value.
38 * @param {Array} list The list to iterate over.
39 * @return {*} The final, accumulated value.
40 * @see R.reduced, R.addIndex, R.reduceRight
41 * @example
42 *
43 * R.reduce(R.subtract, 0, [1, 2, 3, 4]) // => ((((0 - 1) - 2) - 3) - 4) = -10
44 * // - -10
45 * // / \ / \
46 * // - 4 -6 4
47 * // / \ / \
48 * // - 3 ==> -3 3
49 * // / \ / \
50 * // - 2 -1 2
51 * // / \ / \
52 * // 0 1 0 1
53 *
54 * @symb R.reduce(f, a, [b, c, d]) = f(f(f(a, b), c), d)
55 */
56
57var reduce =
58/*#__PURE__*/
59_curry3(function (xf, acc, list) {
60 return _xReduce(typeof xf === 'function' ? _xwrap(xf) : xf, acc, list);
61});
62
63export default reduce;
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