756 lines
19 KiB
JavaScript
756 lines
19 KiB
JavaScript
/**
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* A data type for immutable linked lists representing ordered collections of elements of type `A`.
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*
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* This data type is optimal for last-in-first-out (LIFO), stack-like access patterns. If you need another access pattern, for example, random access or FIFO, consider using a collection more suited to this than `List`.
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*
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* **Performance**
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*
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* - Time: `List` has `O(1)` prepend and head/tail access. Most other operations are `O(n)` on the number of elements in the list. This includes the index-based lookup of elements, `length`, `append` and `reverse`.
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* - Space: `List` implements structural sharing of the tail list. This means that many operations are either zero- or constant-memory cost.
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*
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* @since 2.0.0
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*/
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/**
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* This file is ported from
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*
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* Scala (https://www.scala-lang.org)
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*
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* Copyright EPFL and Lightbend, Inc.
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*
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* Licensed under Apache License 2.0
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* (http://www.apache.org/licenses/LICENSE-2.0).
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*/
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import * as Arr from "./Array.js";
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import * as Chunk from "./Chunk.js";
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import * as Either from "./Either.js";
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import * as Equal from "./Equal.js";
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import * as Equivalence from "./Equivalence.js";
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import { dual, identity, unsafeCoerce } from "./Function.js";
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import * as Hash from "./Hash.js";
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import { format, NodeInspectSymbol, toJSON } from "./Inspectable.js";
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import * as Option from "./Option.js";
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import { pipeArguments } from "./Pipeable.js";
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import { hasProperty } from "./Predicate.js";
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/**
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* @since 2.0.0
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* @category symbol
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*/
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export const TypeId = /*#__PURE__*/Symbol.for("effect/List");
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/**
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* Converts the specified `List` to an `Array`.
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*
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* @category conversions
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* @since 2.0.0
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*/
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export const toArray = self => Arr.fromIterable(self);
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/**
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* @category equivalence
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* @since 2.0.0
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*/
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export const getEquivalence = isEquivalent => Equivalence.mapInput(Arr.getEquivalence(isEquivalent), toArray);
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const _equivalence = /*#__PURE__*/getEquivalence(Equal.equals);
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const ConsProto = {
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[TypeId]: TypeId,
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_tag: "Cons",
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toString() {
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return format(this.toJSON());
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},
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toJSON() {
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return {
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_id: "List",
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_tag: "Cons",
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values: toArray(this).map(toJSON)
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};
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},
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[NodeInspectSymbol]() {
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return this.toJSON();
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},
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[Equal.symbol](that) {
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return isList(that) && this._tag === that._tag && _equivalence(this, that);
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},
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[Hash.symbol]() {
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return Hash.cached(this, Hash.array(toArray(this)));
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},
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[Symbol.iterator]() {
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let done = false;
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// eslint-disable-next-line @typescript-eslint/no-this-alias
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let self = this;
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return {
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next() {
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if (done) {
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return this.return();
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}
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if (self._tag === "Nil") {
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done = true;
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return this.return();
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}
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const value = self.head;
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self = self.tail;
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return {
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done,
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value
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};
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},
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return(value) {
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if (!done) {
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done = true;
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}
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return {
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done: true,
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value
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};
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}
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};
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},
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pipe() {
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return pipeArguments(this, arguments);
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}
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};
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const makeCons = (head, tail) => {
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const cons = Object.create(ConsProto);
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cons.head = head;
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cons.tail = tail;
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return cons;
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};
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const NilHash = /*#__PURE__*/Hash.string("Nil");
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const NilProto = {
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[TypeId]: TypeId,
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_tag: "Nil",
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toString() {
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return format(this.toJSON());
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},
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toJSON() {
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return {
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_id: "List",
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_tag: "Nil"
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};
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},
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[NodeInspectSymbol]() {
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return this.toJSON();
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},
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[Hash.symbol]() {
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return NilHash;
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},
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[Equal.symbol](that) {
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return isList(that) && this._tag === that._tag;
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},
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[Symbol.iterator]() {
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return {
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next() {
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return {
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done: true,
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value: undefined
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};
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}
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};
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},
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pipe() {
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return pipeArguments(this, arguments);
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}
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};
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const _Nil = /*#__PURE__*/Object.create(NilProto);
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/**
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* Returns `true` if the specified value is a `List`, `false` otherwise.
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*
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* @since 2.0.0
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* @category refinements
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*/
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export const isList = u => hasProperty(u, TypeId);
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/**
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* Returns `true` if the specified value is a `List.Nil<A>`, `false` otherwise.
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*
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* @since 2.0.0
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* @category refinements
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*/
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export const isNil = self => self._tag === "Nil";
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/**
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* Returns `true` if the specified value is a `List.Cons<A>`, `false` otherwise.
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*
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* @since 2.0.0
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* @category refinements
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*/
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export const isCons = self => self._tag === "Cons";
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/**
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* Returns the number of elements contained in the specified `List`
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*
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* @since 2.0.0
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* @category getters
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*/
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export const size = self => {
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let these = self;
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let len = 0;
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while (!isNil(these)) {
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len += 1;
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these = these.tail;
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}
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return len;
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};
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/**
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* Constructs a new empty `List<A>`.
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*
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* @since 2.0.0
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* @category constructors
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*/
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export const nil = () => _Nil;
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/**
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* Constructs a new `List.Cons<A>` from the specified `head` and `tail` values.
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*
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* @since 2.0.0
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* @category constructors
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*/
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export const cons = (head, tail) => makeCons(head, tail);
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/**
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* Constructs a new empty `List<A>`.
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*
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* Alias of {@link nil}.
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*
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* @since 2.0.0
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* @category constructors
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*/
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export const empty = nil;
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/**
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* Constructs a new `List<A>` from the specified value.
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*
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* @since 2.0.0
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* @category constructors
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*/
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export const of = value => makeCons(value, _Nil);
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/**
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* Creates a new `List` from an iterable collection of values.
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*
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* @since 2.0.0
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* @category constructors
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*/
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export const fromIterable = prefix => {
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const iterator = prefix[Symbol.iterator]();
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let next;
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if ((next = iterator.next()) && !next.done) {
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const result = makeCons(next.value, _Nil);
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let curr = result;
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while ((next = iterator.next()) && !next.done) {
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const temp = makeCons(next.value, _Nil);
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curr.tail = temp;
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curr = temp;
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}
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return result;
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} else {
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return _Nil;
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}
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};
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/**
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* Constructs a new `List<A>` from the specified values.
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*
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* @since 2.0.0
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* @category constructors
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*/
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export const make = (...elements) => fromIterable(elements);
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/**
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* Appends the specified element to the end of the `List`, creating a new `Cons`.
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*
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* @category concatenating
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* @since 2.0.0
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*/
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export const append = /*#__PURE__*/dual(2, (self, element) => appendAll(self, of(element)));
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/**
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* Concatenates two lists, combining their elements.
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* If either list is non-empty, the result is also a non-empty list.
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*
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* @example
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* ```ts
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* import * as assert from "node:assert"
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* import { List } from "effect"
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*
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* assert.deepStrictEqual(
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* List.make(1, 2).pipe(List.appendAll(List.make("a", "b")), List.toArray),
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* [1, 2, "a", "b"]
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* )
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* ```
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*
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* @category concatenating
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* @since 2.0.0
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*/
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export const appendAll = /*#__PURE__*/dual(2, (self, that) => prependAll(that, self));
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/**
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* Prepends the specified element to the beginning of the list.
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*
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* @category concatenating
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* @since 2.0.0
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*/
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export const prepend = /*#__PURE__*/dual(2, (self, element) => cons(element, self));
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/**
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* Prepends the specified prefix list to the beginning of the specified list.
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* If either list is non-empty, the result is also a non-empty list.
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*
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* @example
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* ```ts
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* import * as assert from "node:assert"
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* import { List } from "effect"
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*
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* assert.deepStrictEqual(
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* List.make(1, 2).pipe(List.prependAll(List.make("a", "b")), List.toArray),
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* ["a", "b", 1, 2]
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* )
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* ```
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*
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* @category concatenating
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* @since 2.0.0
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*/
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export const prependAll = /*#__PURE__*/dual(2, (self, prefix) => {
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if (isNil(self)) {
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return prefix;
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} else if (isNil(prefix)) {
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return self;
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} else {
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const result = makeCons(prefix.head, self);
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let curr = result;
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let that = prefix.tail;
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while (!isNil(that)) {
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const temp = makeCons(that.head, self);
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curr.tail = temp;
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curr = temp;
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that = that.tail;
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}
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return result;
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}
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});
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/**
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* Prepends the specified prefix list (in reverse order) to the beginning of the
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* specified list.
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*
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* @category concatenating
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* @since 2.0.0
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*/
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export const prependAllReversed = /*#__PURE__*/dual(2, (self, prefix) => {
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let out = self;
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let pres = prefix;
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while (isCons(pres)) {
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out = makeCons(pres.head, out);
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pres = pres.tail;
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}
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return out;
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});
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/**
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* Drops the first `n` elements from the specified list.
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*
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* @since 2.0.0
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* @category combinators
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*/
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export const drop = /*#__PURE__*/dual(2, (self, n) => {
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if (n <= 0) {
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return self;
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}
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if (n >= size(self)) {
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return _Nil;
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}
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let these = self;
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let i = 0;
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while (!isNil(these) && i < n) {
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these = these.tail;
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i += 1;
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}
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return these;
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});
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/**
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* Check if a predicate holds true for every `List` element.
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*
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* @since 2.0.0
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* @category elements
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*/
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export const every = /*#__PURE__*/dual(2, (self, refinement) => {
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for (const a of self) {
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if (!refinement(a)) {
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return false;
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}
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}
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return true;
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});
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/**
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* Check if a predicate holds true for some `List` element.
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*
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* @since 2.0.0
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* @category elements
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*/
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export const some = /*#__PURE__*/dual(2, (self, predicate) => {
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let these = self;
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while (!isNil(these)) {
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if (predicate(these.head)) {
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return true;
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}
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these = these.tail;
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}
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return false;
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});
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/**
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* Filters a list using the specified predicate.
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*
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* @since 2.0.0
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* @category combinators
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*/
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export const filter = /*#__PURE__*/dual(2, (self, predicate) => noneIn(self, predicate, false));
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// everything seen so far is not included
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const noneIn = (self, predicate, isFlipped) => {
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while (true) {
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if (isNil(self)) {
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return _Nil;
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} else {
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if (predicate(self.head) !== isFlipped) {
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return allIn(self, self.tail, predicate, isFlipped);
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} else {
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self = self.tail;
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}
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}
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}
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};
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// everything from 'start' is included, if everything from this point is in we can return the origin
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// start otherwise if we discover an element that is out we must create a new partial list.
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const allIn = (start, remaining, predicate, isFlipped) => {
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while (true) {
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if (isNil(remaining)) {
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return start;
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} else {
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if (predicate(remaining.head) !== isFlipped) {
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remaining = remaining.tail;
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} else {
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return partialFill(start, remaining, predicate, isFlipped);
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}
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}
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}
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};
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// we have seen elements that should be included then one that should be excluded, start building
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const partialFill = (origStart, firstMiss, predicate, isFlipped) => {
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const newHead = makeCons(unsafeHead(origStart), _Nil);
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let toProcess = unsafeTail(origStart);
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let currentLast = newHead;
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// we know that all elements are :: until at least firstMiss.tail
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while (!(toProcess === firstMiss)) {
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const newElem = makeCons(unsafeHead(toProcess), _Nil);
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currentLast.tail = newElem;
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currentLast = unsafeCoerce(newElem);
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toProcess = unsafeCoerce(toProcess.tail);
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}
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// at this point newHead points to a list which is a duplicate of all the 'in' elements up to the first miss.
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// currentLast is the last element in that list.
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// now we are going to try and share as much of the tail as we can, only moving elements across when we have to.
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let next = firstMiss.tail;
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let nextToCopy = unsafeCoerce(next); // the next element we would need to copy to our list if we cant share.
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while (!isNil(next)) {
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// generally recommended is next.isNonEmpty but this incurs an extra method call.
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const head = unsafeHead(next);
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if (predicate(head) !== isFlipped) {
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next = next.tail;
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} else {
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// its not a match - do we have outstanding elements?
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while (!(nextToCopy === next)) {
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const newElem = makeCons(unsafeHead(nextToCopy), _Nil);
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currentLast.tail = newElem;
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currentLast = newElem;
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nextToCopy = unsafeCoerce(nextToCopy.tail);
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}
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nextToCopy = unsafeCoerce(next.tail);
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next = next.tail;
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}
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}
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// we have remaining elements - they are unchanged attach them to the end
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if (!isNil(nextToCopy)) {
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currentLast.tail = nextToCopy;
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}
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return newHead;
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};
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/**
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* Filters and maps a list using the specified partial function. The resulting
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* list may be smaller than the input list due to the possibility of the partial
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* function not being defined for some elements.
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*
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* @since 2.0.0
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* @category combinators
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*/
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export const filterMap = /*#__PURE__*/dual(2, (self, f) => {
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const bs = [];
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for (const a of self) {
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const oa = f(a);
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if (Option.isSome(oa)) {
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bs.push(oa.value);
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}
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}
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return fromIterable(bs);
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});
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/**
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* Removes all `None` values from the specified list.
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*
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* @since 2.0.0
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* @category combinators
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*/
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export const compact = self => filterMap(self, identity);
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/**
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* Returns the first element that satisfies the specified
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* predicate, or `None` if no such element exists.
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*
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* @category elements
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* @since 2.0.0
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*/
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export const findFirst = /*#__PURE__*/dual(2, (self, predicate) => {
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let these = self;
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while (!isNil(these)) {
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if (predicate(these.head)) {
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return Option.some(these.head);
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}
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these = these.tail;
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}
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return Option.none();
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});
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/**
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* Applies a function to each element in a list and returns a new list containing the concatenated mapped elements.
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*
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* @since 2.0.0
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* @category sequencing
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*/
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export const flatMap = /*#__PURE__*/dual(2, (self, f) => {
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let rest = self;
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let head = undefined;
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let tail = undefined;
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while (!isNil(rest)) {
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let bs = f(rest.head);
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while (!isNil(bs)) {
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const next = makeCons(bs.head, _Nil);
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if (tail === undefined) {
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head = next;
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} else {
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tail.tail = next;
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}
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tail = next;
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bs = bs.tail;
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}
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rest = rest.tail;
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}
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if (head === undefined) {
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return _Nil;
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}
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return head;
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});
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/**
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* Applies the specified function to each element of the `List`.
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*
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* @since 2.0.0
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* @category combinators
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*/
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export const forEach = /*#__PURE__*/dual(2, (self, f) => {
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let these = self;
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while (!isNil(these)) {
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f(these.head);
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these = these.tail;
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}
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});
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/**
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* Returns the first element of the specified list, or `None` if the list is
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* empty.
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*
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* @since 2.0.0
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* @category getters
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*/
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export const head = self => isNil(self) ? Option.none() : Option.some(self.head);
|
|
/**
|
|
* Returns the last element of the specified list, or `None` if the list is
|
|
* empty.
|
|
*
|
|
* @since 2.0.0
|
|
* @category getters
|
|
*/
|
|
export const last = self => isNil(self) ? Option.none() : Option.some(unsafeLast(self));
|
|
/**
|
|
* Applies the specified mapping function to each element of the list.
|
|
*
|
|
* @since 2.0.0
|
|
* @category mapping
|
|
*/
|
|
export const map = /*#__PURE__*/dual(2, (self, f) => {
|
|
if (isNil(self)) {
|
|
return self;
|
|
} else {
|
|
let i = 0;
|
|
const head = makeCons(f(self.head, i++), _Nil);
|
|
let nextHead = head;
|
|
let rest = self.tail;
|
|
while (!isNil(rest)) {
|
|
const next = makeCons(f(rest.head, i++), _Nil);
|
|
nextHead.tail = next;
|
|
nextHead = next;
|
|
rest = rest.tail;
|
|
}
|
|
return head;
|
|
}
|
|
});
|
|
/**
|
|
* Partition a list into two lists, where the first list contains all elements
|
|
* that did not satisfy the specified predicate, and the second list contains
|
|
* all elements that did satisfy the specified predicate.
|
|
*
|
|
* @since 2.0.0
|
|
* @category combinators
|
|
*/
|
|
export const partition = /*#__PURE__*/dual(2, (self, predicate) => {
|
|
const left = [];
|
|
const right = [];
|
|
for (const a of self) {
|
|
if (predicate(a)) {
|
|
right.push(a);
|
|
} else {
|
|
left.push(a);
|
|
}
|
|
}
|
|
return [fromIterable(left), fromIterable(right)];
|
|
});
|
|
/**
|
|
* Partition a list into two lists, where the first list contains all elements
|
|
* for which the specified function returned a `Left`, and the second list
|
|
* contains all elements for which the specified function returned a `Right`.
|
|
*
|
|
* @since 2.0.0
|
|
* @category combinators
|
|
*/
|
|
export const partitionMap = /*#__PURE__*/dual(2, (self, f) => {
|
|
const left = [];
|
|
const right = [];
|
|
for (const a of self) {
|
|
const e = f(a);
|
|
if (Either.isLeft(e)) {
|
|
left.push(e.left);
|
|
} else {
|
|
right.push(e.right);
|
|
}
|
|
}
|
|
return [fromIterable(left), fromIterable(right)];
|
|
});
|
|
/**
|
|
* Folds over the elements of the list using the specified function, using the
|
|
* specified initial value.
|
|
*
|
|
* @since 2.0.0
|
|
* @category folding
|
|
*/
|
|
export const reduce = /*#__PURE__*/dual(3, (self, zero, f) => {
|
|
let acc = zero;
|
|
let these = self;
|
|
while (!isNil(these)) {
|
|
acc = f(acc, these.head);
|
|
these = these.tail;
|
|
}
|
|
return acc;
|
|
});
|
|
/**
|
|
* Folds over the elements of the list using the specified function, beginning
|
|
* with the last element of the list, using the specified initial value.
|
|
*
|
|
* @since 2.0.0
|
|
* @category folding
|
|
*/
|
|
export const reduceRight = /*#__PURE__*/dual(3, (self, zero, f) => {
|
|
let acc = zero;
|
|
let these = reverse(self);
|
|
while (!isNil(these)) {
|
|
acc = f(acc, these.head);
|
|
these = these.tail;
|
|
}
|
|
return acc;
|
|
});
|
|
/**
|
|
* Returns a new list with the elements of the specified list in reverse order.
|
|
*
|
|
* @since 2.0.0
|
|
* @category elements
|
|
*/
|
|
export const reverse = self => {
|
|
let result = empty();
|
|
let these = self;
|
|
while (!isNil(these)) {
|
|
result = prepend(result, these.head);
|
|
these = these.tail;
|
|
}
|
|
return result;
|
|
};
|
|
/**
|
|
* Splits the specified list into two lists at the specified index.
|
|
*
|
|
* @since 2.0.0
|
|
* @category combinators
|
|
*/
|
|
export const splitAt = /*#__PURE__*/dual(2, (self, n) => [take(self, n), drop(self, n)]);
|
|
/**
|
|
* Returns the tail of the specified list, or `None` if the list is empty.
|
|
*
|
|
* @since 2.0.0
|
|
* @category getters
|
|
*/
|
|
export const tail = self => isNil(self) ? Option.none() : Option.some(self.tail);
|
|
/**
|
|
* Takes the specified number of elements from the beginning of the specified
|
|
* list.
|
|
*
|
|
* @since 2.0.0
|
|
* @category combinators
|
|
*/
|
|
export const take = /*#__PURE__*/dual(2, (self, n) => {
|
|
if (n <= 0) {
|
|
return _Nil;
|
|
}
|
|
if (n >= size(self)) {
|
|
return self;
|
|
}
|
|
let these = make(unsafeHead(self));
|
|
let current = unsafeTail(self);
|
|
for (let i = 1; i < n; i++) {
|
|
these = makeCons(unsafeHead(current), these);
|
|
current = unsafeTail(current);
|
|
}
|
|
return reverse(these);
|
|
});
|
|
/**
|
|
* Converts the specified `List` to a `Chunk`.
|
|
*
|
|
* @since 2.0.0
|
|
* @category conversions
|
|
*/
|
|
export const toChunk = self => Chunk.fromIterable(self);
|
|
const getExpectedListToBeNonEmptyErrorMessage = "Expected List to be non-empty";
|
|
/**
|
|
* Unsafely returns the first element of the specified `List`.
|
|
*
|
|
* @since 2.0.0
|
|
* @category unsafe
|
|
*/
|
|
export const unsafeHead = self => {
|
|
if (isNil(self)) {
|
|
throw new Error(getExpectedListToBeNonEmptyErrorMessage);
|
|
}
|
|
return self.head;
|
|
};
|
|
/**
|
|
* Unsafely returns the last element of the specified `List`.
|
|
*
|
|
* @since 2.0.0
|
|
* @category unsafe
|
|
*/
|
|
export const unsafeLast = self => {
|
|
if (isNil(self)) {
|
|
throw new Error(getExpectedListToBeNonEmptyErrorMessage);
|
|
}
|
|
let these = self;
|
|
let scout = self.tail;
|
|
while (!isNil(scout)) {
|
|
these = scout;
|
|
scout = scout.tail;
|
|
}
|
|
return these.head;
|
|
};
|
|
/**
|
|
* Unsafely returns the tail of the specified `List`.
|
|
*
|
|
* @since 2.0.0
|
|
* @category unsafe
|
|
*/
|
|
export const unsafeTail = self => {
|
|
if (isNil(self)) {
|
|
throw new Error(getExpectedListToBeNonEmptyErrorMessage);
|
|
}
|
|
return self.tail;
|
|
};
|
|
//# sourceMappingURL=List.js.map
|