monadanator v2.0.0

Monadanator

When you want to make things pure and functional.

Usage

Container

Basic container that both a functor and a monad. It responds to map and flatMap. In addition, it also responds to of and ap.

of describes a pointed monad where as ap describes an applicative monad.

examples

import { container } from 'monadanator'

container(3)
  .map(three => three * 2)
  .flatMap(six => container.of(2)
    .map(two => two * six)
  )
  .map(twelve => console.log(twelve))

container
  .of(x => console.log(x))
  .ap('something that will get logged')
  .ap(container.of('another thing that will be logged'))

IO

provides a function that acts just like container, but implements the expected IO Monad behaviour.

The only difference between an IO monad and a Container monad is that an IO monad waits to execute any calls to map, flatMap or ap. These calls will only be run when perform is called.

examples

import { io } from 'monadanator'

const helloWorld = io.of(window)
  .map(w => window.alert('hello world')) // no alert

helloWorld.perform() // alert's hello world

alternatively, you could use the run helper function

import { io, helpers: { run } } from 'monadanator'

const helloWorld = io.of(window)
  .map(w => window.alert('hello world'));

const append = io.of(document)
  .map(doc => document.body.appendChild('hello!'))

run(
  helloWorld,
  append
) //alerts hello world & appends child

Maybe

Maybe represents a point in your program where things could go wrong. It works exactly like a container, except when it receives a value of undefined or null. At which point, map, flatMap and ap will stop running.

There is also error method that will only run if the value contained within the Maybe monad is either undefined or null

examples

import { maybe } from 'monadanator'
  maybe.of(true)
    .map(x => !x)
    .map(x => undefined) // everything past this point will never run
    .flatMap(x => maybe.of(3).map(x => * 2))
    .map(six => console.log(six))
    .error(_ => console.log('something went wrong')) // runs because the monad contains undefined