Introduction to Flow

This is a simple piece of boilerplate that gives some examples of how to get started with Facebook's Flow gradual typing system for JavaScript.

Dependencies

To install dependencies:

npm install

Paths

To avoid having to install flow and babel globally, be sure to add the node_modules/.bin folder to your path:

export PATH=./node_modules/.bin:$PATH

Type checking

To get a status report of what is potentially wrong with ALL your code, simply run:

npm run flow

If you want to check just a single file then you can do:

cat exercise_01.js | flow check-contents

Running your code

In order to run your code without transpiling you can use the babel CLI:

babel-node exercise_01.js

(Don't forget the PATH advice above!)

Exercises

Can be found in files exercise_01.js through exercise_0?.js

IDE integration

You can add flow type-checking on save to Atom by using the 'ide-flow' plugin.