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Build status NPM version Dependencies status Licence Experimental

Interface checking for JS values


// In Sweet.js
$contract{ Any | Array<Any> -> Array<Any> } :: function(a) {
  return Array.isArray(a)? a : [a]

// In JS
c.contract([c.Union(c.Any, c.Array(c.Any))], c.Array(c.Any))(function(a) {
  return Array.isArray(a)? a : [a]


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

$ npm install core.check

Using with CommonJS

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

var Check = require('core.check')

Using with AMD

Download the latest release, and require the core.check.umd.js file:

require(['core.check'], function(Check) {
  ( ... )

Using without modules

Download the latest release, and load the core.check.umd.js file. The properties are exposed in the global Folktale.Core.Check object:

<script src="/path/to/core.check.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 core.check
$ npm install
$ make bundle

This will generate the dist/core.check.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 core.check
$ npm install
$ make documentation

Then open the file docs/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) 2014 Quildreen Motta.

Released under the MIT licence.