A disjunction that's more appropriate for validating inputs with better vocabulary & straight-forward failure aggregation.

Please use data.validation instead.
Last updated 7 years ago by killdream .
MIT · Repository · Bugs · Original npm · Tarball · package.json
$ cnpm install applicative.validation 
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Applicative: Validation

Build Status NPM version Dependencies Status experimental

The Validation(a, b) is a disjunction that's more appropriate for validating inputs, or any use case where you want to aggregate failures. Not only the Validation provides a better terminology for working with such cases (Failure and Success versus Left and Right), it also allows one to easily aggregate failures and successes as an Applicative Functor.


var Validation = require(applicatives.validation')
var Success = Validation.Success
var Failure = Validation.Failure

function isPasswordLongEnough(a) {
  return a.length > 6?    Success(a)
  :      /* otherwise */  Failure("Password must have more than 6 characters")

function isPasswordStrongEnough(a) {
  return /[\W]/.test(a)?  Success(a)
  :      /* otherwise */  Failure("Password must contain special characters")

function isPasswordValid(a) {
  return [isPasswordLongEnough(a), isPasswordStrongEnough(a)]
           .map(function(x){ return x.bimap(liftNel, k) })
           .reduce(function(a, b) { return a.ap(b) })

function liftNel(a) {
  return [a]

function k(a){ return function(b) {
  return a

// => Validation.Failure([
//      "Password must have more than 6 characters.",
//      "Password must contain special characters."
//    ])

// => Validation.Failure([
//      "Password must contain special characters."
//    ])

// => Validation.Success("rosesarered$andstuff")


The easiest way is to grab it from NPM. If you're running in a Browser environment, you can use Browserify

$ npm install applicatives.validation

Using with CommonJS

If you're not using NPM, Download the latest release, and require the applicatives.validation.umd.js file:

var Validation = require('applicatives.validation')

Using with AMD

Download the latest release, and require the applicatives.validation.umd.js file:

require(['applicatives.validation'], function(Validation) {
  ( ... )

Using without modules

Download the latest release, and load the applicatives.validation.umd.js file. The properties are exposed in the global folktale.applicatives.Validation object:

<script src="/path/to/applicatives.validation.umd.js"></script>

Compiling from source

If you want to compile this library from the source, you'll need Git, Make, Node.js, and run the following commands:

$ git clone git://
$ cd applicatives.validation
$ npm install
$ make bundle

This will generate the dist/applicatives.validation.umd.js file, which you can load in any JavaScript environment.


You can read the documentation online or build it yourself:

$ git clone git://
$ cd applicatives.validation
$ npm install
$ make documentation

Then open the file docs/literate/index.html in your browser.

Platform support

This library assumes an ES5 environment, but can be easily supported in ES3 platforms by the use of shims. Just include es5-shim :)


Copyright (c) 2013 Quildreen Motta.

Released under the MIT licence.

Current Tags

  • 0.3.0                                ...           latest (7 years ago)

1 Versions

  • 0.3.0 [deprecated]           ...           7 years ago
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