typescript-monads's Introduction

📚 typescript-monads

Better TypeScript Control Flow

typescript-monads helps you write safer code by using abstractions over messy control flow and state.

Installation

You can use this library in the browser, node, or a bundler

Node or as a module

npm install typescript-monads

Browser

<head>
 <script src="https://unpkg.com/typescript-monads"></script>
 <!-- or use a specific version to avoid a redirect --> 
 <script src="https://unpkg.com/[email protected]/index.min.js"></script>
</head>

var someRemoteValue;
typescriptMonads.maybe(someRemoteValue).tapSome(console.log)

Example Usage

Maybe
Either
Reader
Result

Maybe

import { maybe } from 'typescript-monads'

// safely map values
let maybeVisitedBeforeXTimes: number | undefined = 50

const priceWithDiscountForLoyalty = maybe(maybeVisitedBeforeXTimes)
  .match({
    some: visits => 15.00 - visits * 0.1,
    none: () => 15.00
  })

// handle multiple maybe conditionas together
const canRideCoaster = getAge() // Maybe<number>
  .bind(age => getTicket(age)) // Maybe<Ticket>
  .match({
    some: ticket => ticket.canRide('coaster1'),
    none: () => false
  })

// operations with side-effects
maybe(process.env.DB_URL)
  .do({
    some: dbUrl => {
      // value exists, can connect
    },
    none: () => console.info('no url provided, could not connect to the database')
  })