Pure function to update elements in array that are equal in Typescript
Sandro Maglione
Get in touch with meWeb development
16 January 2022
•1 min read
Sandro Maglione
Web development
This function allows you to update all the elements in a given array that match the given Eq instance.
This is a pure function (without side-effects) based on functional programming using fp-ts.
updateWhere.ts
import * as A from "fp-ts/Array";
import * as Eq from "fp-ts/Eq";
import { flow } from "fp-ts/function";
/**
* Update an element inside an array using the given instance of `Eq`
* @param element Element to search in the array
* @param eq Instance of `Eq` to compare two elements
* @returns The given array with the element equal to `element` update (if found)
*/
export const updateWhere =
<T>(element: T, eq: Eq.Eq<T>) =>
(update: T): ((array: T[]) => T[]) =>
flow(A.map((t) => (eq.equals(t, element) ? update : t)));