Introduction

Taowei is a functional, iterable-focused JavaScript library.

This is a curiosity-driven project that provides a set of utilities that make working with iterables and functional programming more intuitive and elegant.

Goals

• Keep simple and fun
• Built for lazy reusable iterables
• Readable code
• Curried, functional-style composable, with a love for point-free programming
• Provide enough functions to cover most common programmer needs, allowing easy composition.
• Taowei should be fun to develop (with concise and clear implementations) and fun to use
• 100% test coverage
• Comprehensive documentation

Non-goals

• Performance optimizations
• TypeScript support
• Async support

Usage

Node.js

Install via npm:

npm install taowei

And use it:

import { isEven } from 'taowei'

console.log(isEven(5)) // false

Browser

Use directly via CDN:

import { isEven } from 'https://unpkg.com/taowei'

console.log(isEven(5)) // false

Examples

Project Euler #1

Find the sum of all multiples of 3 or 5 below 1000. https://projecteuler.net/problem=1

import { sum, filter, or, isDivisibleBy as isMultipleOf, enumFromTo } from 'taowei'

const nums = enumFromTo(1)(999)
const predicate = or(isMultipleOf(3))(isMultipleOf(5))
const filtered = filter(predicate)(nums)

console.log(sum(filtered)) // 233168

Project Euler #2

By considering the terms in the Fibonacci sequence whose values do not exceed four million, find the sum of the even-valued terms. https://projecteuler.net/problem=2

import { withPrevious, takeWhile, isLesserThanOrEqualTo as lte, 
  repeat, sum, filter, concat, isEven } from 'taowei'

const fibonacci = withPrevious(2)(concat([1, 2, repeat(sum)]))
const evenFibonacci = filter(isEven)(fibonacci)
const firstEvenFibonacci = takeWhile(lte(4_000_000))(evenFibonacci)

console.log(sum(firstEvenFibonacci)) // 4613

For more examples, check out the integration tests.

Testing

To run tests, use:

npm run test