functional-data-structure/persistent

export function heap(empty, max) {
    const Heap = function (tree) {
        this.tree = tree;
    };

    Heap.prototype.isEmpty = function () {
        return this.tree.isEmpty();
    };

    Heap.prototype.maxKey = Heap.prototype.measure = function () {
        return this.tree.measure();
    };

    Heap.prototype.insert = Heap.prototype.push = function (value) {
        return new Heap(this.tree.push(value));
    };

    Heap.prototype.extractMax = function () {
        const ub = this.measure();
        const split = this.tree.splitTree((m) => m >= ub, max.zero());
        return [split.middle, new Heap(split.left.concat(split.right))];
    };

    Heap.prototype.insertValues = function (values) {
        let s = this;

        for (const value of values) s = s.insert(value);

        return s;
    };

    return {
        empty: () => new Heap(empty(max)),
        from: (iterable) => new Heap(empty(max)).insertValues(iterable),
    };
}