Function update

Applies a transformation to the value of an array at the specified index.

Negative indices count backwards from the end of the array. If index is fractional or otherwise invalid, returns a shallow copy of the array.

Example

import * as A from "flurp/array";
import * as N from "flurp/number";

const doubleFirst = A.update(0, N.multiply(2));
doubleFirst([3, 4, 5, 6]);   // [6, 4, 5, 6]

const doubleLast = A.update(-1, N.multiply(2));
doubleLast([3, 4, 5, 6]);   // [3, 4, 5, 12]