import * as O from "./optics.ts";
import { pipe } from "./fn.ts";

type Person = { name: string, age: number };
type State = { people: readonly Person[], format: (p: Person) => string };

const fmt = pipe(O.id<State>(), O.prop("format"));
const adults = pipe(
  O.id<State>(),
  O.prop("people"),
  O.array,
  O.filter(p => p.age > 18)
);

const formatted = pipe(fmt, O.apply(adults));

const result = formatted.view({
  people: [
    { name: "Brandon", age: 37 },
    { name: "Rufus", age: 1 },
  ],
  format: p => `${p.name} is ${p.age}`,
}); // [ "Brandon is 37" ]