import type { NonEmptyArray } from "./array.ts";

import * as O from "./optic.ts";
import * as A from "./array.ts";
import { pipe } from "./fn.ts";

const head = <A>() => O.lens<NonEmptyArray<A>, A>(
  ([head]) => head,
  mod => ([head, ...rest]) => [mod(head), ...rest],
);

const headNum = head<number>();

const result1 = headNum.view(A.array(1, 2, 3)); // 1
const result2 = headNum.modify((n: number) => n + 100)(A.array(1, 2, 3));
// [100, 2, 3]