@hyperjump/pact

Hyperjump Pact

Hyperjump Pact is a utility library that provides higher order functions for working with iterators and async iterators.

Installation

Designed for node.js (ES Modules, TypeScript) and browsers.

npm install @hyperjump/pact --save

Usage

import { pipe, range, map, filter, reduce, asyncMap, asyncFilter, asyncReduce } from "./lib/index.js";


const foo = pipe(
  range(1, 10),
  filter((n) => n % 2 === 0),
  map((n) => n * 2),
  reduce((sum, n) => sum + n, 0)
);
console.log(foo);

const asyncSequence = async function* () {
  yield Promise.resolve(1);
  yield Promise.resolve(2);
  yield Promise.resolve(3);
  yield Promise.resolve(4);
  yield Promise.resolve(5);
};

for await (const value of asyncSequence()) {
  console.log(value);
}

const asyncFoo = await pipe(
  asyncSequence(),
  asyncFilter((n) => n % 2 === 0),
  asyncMap((n) => n * 2),
  asyncReduce((sum, n) => sum + n, 0)
);
console.log(asyncFoo);

API

• map: (fn: Function, iterator: Iterable) => Generator

  Apply a function to every value in the iterator

• asyncMap: (fn: Function, iterator: AsyncIterable) => AsyncGenerator

  Same as map, but works with promises.

• filter: (fn: Function, iterator: Iterable) => Generator

  Yields only the values in the iterator that pass the predicate function.

• asyncFilter: (fn: Function, iterator: AsyncIterable) => AsyncGenerator

  Same as filter, but works with promises.

• drop: (n: number, iterator: Iterable) => Generator

  Yields all the values in the iterator except for the first n values.

• asyncDrop: (n: number, iterator: AsyncIterable) => AsyncGenerator

  Same as drop, but works with promises.

• take: (n: number, iterator: Iterable) => Generator

  Yields the first n values in the iterator.

• asyncTake: (count: number, iterator: AsyncIterable) => AsyncGenerator

  Same as take, but works with promises.

• range: (from: number, to?: number) => Generator

  Yields numbers starting from from until to. If to is not passed, the iterator will be infinite.

• zip: (iter1: Iterable, iter2: Iterable) => Generator

  Yields tuples containing a value from each iterator. The iterator will have the same length as iter1. If iter1 is longer than iter2, the second value of the tuple will be undefined. If iter2 is longer than iter1, the remaining values in iter2 will be ignored.

• asyncZip: (iter1: AsyncIterable, iter2: AsyncIterable) => AsyncGenerator

  Same as zip but works with promises.

• reduce: (fn: Function, acc: any, iter: Iterable) => any

  Reduce an iterator to a single value.

• asyncReduce: (fn: AsyncReducer, acc: any, iter: AsyncIterable) => Promise

  Same as reduce, but works with promises.

• every: (fn: Function, iterator: Iterable) => boolean

  Returns a boolean indicating whether or not all values in the iterator passes the predicate function.

• asyncEvery: (fn: AsyncPredicate, iterator: AsyncIterable) => Promise

  Same as every, but works with promises.

• some: (fn: Function, iterator: Iterable) => boolean

  Returns a boolean indicating whether or not there exists a value in the iterator that passes the predicate function.

• asyncSome: (fn: AsyncPredicate, iterator: AsyncIterable) => Promise

  Same as some, but works with promises.

• collectArray: (fn: Iterable) => Array;

  Collect all the items in the iterator into an array.

• asyncCollectArray: (fn: AsyncIterable) => Promise;

  Same as collectArray, but works with promises.

• collectSet: (fn: Iterable) => Set;

  Collect all the items in the iterator into a Set.

• asyncCollectSet: (fn: AsyncIterable) => Promise;

  Same as collectSet, but works with promises.

• collectMap: (fn: Iterable) => Map;

  Collect all the key/value tuples in the iterator into a Map.

• asyncCollectMap: (fn: AsyncIterable) => Promise;

  Same as collectMap, but works with promises.

• collectObject: (fn: Iterable) => Object;

  Collect all the key/value tuples in the iterator into an Object.

• asyncCollectObject: (fn: AsyncIterable) => Promise;

  Same as collectObject, but works with promises.

• pipe: (iterator: Iterable | AsyncIterable, ...fns: Function) => any;

  Starting with an iterator, apply any number of functions to transform the values and return the result.

Contributing

Tests

Run the tests

npm test

Run the tests with a continuous test runner

npm test -- --watch