@rpearce/ts-fns

Public domain (LICENSE) Typescript helper functions for copying & pasting into projects. You can try it out here: https://npm.runkit.com/%40rpearce%2Fts-fns.

Most functions export two calling styles, regular and partial application:

// Regular
hasProp('color', { color: 'blue' }) // true

// Partial application
hasPropU('color')({ color: 'blue' }) // true

Special thanks to the following for helping with some typings!

• Hackle Wayne
• Lewis Campbell

Typed functions

Note: many functions have a unary, partial application style counterpart ending in U; e.g., cond also exports condU.

• F
• T
• classNames
• compose2
• compose3
• cond, condU
• constant
• doesPropEq, doesPropEqU
• hasProp, hasPropU
• identity
• insertAt, insertAtU
• isArray
• isFunction
• isFunctor
• isObject
• lift2, lift2U
• lift3, lift3U
• log
• map, mapU
• mapObject, mapObjectU
• omitKeys, omitKeysU
• pickKeys, pickKeysU
• pipe2
• pipe3
• propOr, propOrU
• reduce, reduceU
• reduceRight, reduceRightU
• shuffle
• sum
• takeN, takeNU
• unless, unlessU
• when, whenU
• zip

TODO

• both
• either
• filter
• ifElse
• neither
• pluckKeys
• sortAscBy
• sortDescBy
• ??? Open an issue to request something!

Usage

Copy the functions and types you need into your project.

Example

import {
  doesPropEq,
  doesPropEqU,
  takeN,
  takeNU,
} from './wherever-i-copied-the-helpers-to'

takeN(3, [1, 2, 3, 4])  // [1, 2, 3]
takeNU(3)([1, 2, 3, 4]) // [1, 2, 3]

doesPropEq('color', 'blue', { a: 'foo', b: 'bar', color: 'blue' })  // true
doesPropEqU('color')('blue')({ a: 'foo', b: 'bar', color: 'blue' }) // true

More in-depth unary partial application example

import { lift2U, propOrU } from './wherever-i-copied-the-helpers-to'

const propOrNA      = propOr('N/A')
const getName       = propOrNA('name')
const getEmail      = propOrNA('email')
const joinWithPipe  = (x: string) => (y: string) => `${x} | ${y}`
const joinNameEmail = lift2U(joinWithPipe)(getName)(getEmail)
const input         = { name: 'bobert', email: '[e-mail]', foo: 'bar' }

console.log(joinNameEmail(input))
// 'bobert | [e-mail]'