import * as A from "../Array";
import { identity } from "../Function";
import type { Tree } from "./model";

/*
 * -------------------------------------------
 * Comonad Tree
 * -------------------------------------------
 */

export const extend_ = <A, B>(wa: Tree<A>, f: (wa: Tree<A>) => B): Tree<B> => ({
   value: f(wa),
   forest: A.map_(wa.forest, (a) => extend_(a, f))
});

export const extend = <A, B>(f: (wa: Tree<A>) => B) => (wa: Tree<A>): Tree<B> => extend_(wa, f);

export const duplicate: <A>(wa: Tree<A>) => Tree<Tree<A>> = extend(identity);

export const extract = <A>(wa: Tree<A>): A => wa.value;