46 lines
1.2 KiB
JavaScript
46 lines
1.2 KiB
JavaScript
|
import _curry3 from "./internal/_curry3.js";
|
||
|
|
import _dispatchable from "./internal/_dispatchable.js";
|
||
|
|
import _xscan from "./internal/_xscan.js";
|
||
|
|
/**
|
||
|
|
* Scan is similar to [`reduce`](#reduce), but returns a list of successively
|
||
|
|
* reduced values from the left.
|
||
|
|
*
|
||
|
|
* Acts as a transducer if a transformer is given in list position.
|
||
|
|
*
|
||
|
|
* @func
|
||
|
|
* @memberOf R
|
||
|
|
* @since v0.10.0
|
||
|
|
* @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 {Array} A list of all intermediately reduced values.
|
||
|
|
* @see R.reduce, R.mapAccum
|
||
|
|
* @example
|
||
|
|
*
|
||
|
|
* const numbers = [1, 2, 3, 4];
|
||
|
|
* const factorials = R.scan(R.multiply, 1, numbers); //=> [1, 1, 2, 6, 24]
|
||
|
|
* @symb R.scan(f, a, [b, c]) = [a, f(a, b), f(f(a, b), c)]
|
||
|
|
*/
|
||
|
|
|
||
|
|
var scan =
|
||
|
|
/*#__PURE__*/
|
||
|
|
_curry3(
|
||
|
|
/*#__PURE__*/
|
||
|
|
_dispatchable([], _xscan, function scan(fn, acc, list) {
|
||
|
|
var idx = 0;
|
||
|
|
var len = list.length;
|
||
|
|
var result = [acc];
|
||
|
|
|
||
|
|
while (idx < len) {
|
||
|
|
acc = fn(acc, list[idx]);
|
||
|
|
result[idx + 1] = acc;
|
||
|
|
idx += 1;
|
||
|
|
}
|
||
|
|
|
||
|
|
return result;
|
||
|
|
}));
|
||
|
|
|
||
|
|
export default scan;
|