Validation

[alexeygolev]

Thank you for the library! It's very impressive. I'm trying to wrap my head around validation but struggling to do so. It does seem to be similar to scalaz validation but I'm not sure how would I use it. Any chance for an example? Thank you again

[gcanti]

It does seem to be similar to scalaz validation

Yep. Adapted from http://eed3si9n.com/learning-scalaz/Validation.html

// @flow

import { getApplicative } from 'flow-static-land/lib/Validation'
import * as either from 'flow-static-land/lib/Either'
import { stringMonoid } from 'flow-static-land/lib/Monoid'

const applicative = getApplicative(stringMonoid)

const x = either.right('event 1 ok')
const y = either.left('event 2 failed!')
const z = either.left('event 3 failed!')

const validation = applicative.ap(applicative.ap(applicative.map(a => b => c => a + b + c, x), y), z)

console.log(validation) // => Left {value0: "event 2 failed!event 3 failed!"}