import { RBTreeWrapper } from "../util/rbtree_wrapper.js";
import { newProduct } from "./product.js";
import { newLeft, newRight } from "./sum.js";

export const emptyDict = compareFn => RBTreeWrapper.new((x, y) => compareFn(x)(y));

export const has = dict => key => dict.tree.get(key) === true;
export const set = dict => key => value => new RBTreeWrapper(dict.tree.remove(key).insert(key, value));
export const remove = dict => key => new RBTreeWrapper(dict.tree.remove(key));
export const length = dict => dict.tree.length;

export const first = dict => dict.tree.begin;
export const last  = dict => dict.tree.end;

export const read = iter => {
  if (iter !== undefined && iter.valid) {
    return newRight(newProduct(newProduct(iter.key)(iter.value))(iter.clone().next()));
  }
  else {
    return newLeft(unit);
  }
};