import * as O from "./optic.ts";
import * as M from "./map.ts";
import { ComparableString, toLowerCase } from "./string.ts";
import { premap } from "./comparable.ts";
import { constNone } from "./option.ts";
import { pipe } from "./fn.ts";

type Words = ReadonlyMap<string, number>;

const insensitive = pipe(ComparableString, premap(toLowerCase));

const fun = pipe(O.id<Words>(), O.atMap(insensitive)("fun"));
const remove = pipe(fun, O.replace(constNone()));

const result1 = pipe(fun, O.view(new Map([["FUN", 100]]))); // Some(100)
const result2 = pipe(fun, O.view(M.init())); // None
const result3 = remove(new Map([["FUN", 100], ["not", 10]]));
// Map("not": 10);