Flow

CTO & Co-Founder

Nadav Leshem

Jolt.us

npm install --save-dev \
	flow-bin\
	babel-plugin-transform-flow-strip-types

touch .flowconfig

// @flow

function add(num1: number, num2: number): number {
  return num1 + num2;
}

let myObject: {foo: string, bar: number} =
    {foo: "foo", bar: 0};

let myMap: {[id:string]: number} = {};

myMap["sam"] = 10;

let array: number[] = [1, 2, 3.14, 42];

let array2: Array<string> = 
  ["an alternate", "syntax", "for arrays"];

let tuple: [string, number, boolean] =
     ["foo", 0, true];

class MyClass {
  foo: string;

  constructor(foo: string) {
    this.foo = foo;
  }

  bar(): string {
    return this.foo;
  }
}

function identity<T>(obj: T): T {
  return obj;
}

class Container<T> {
  obj: T;
  constructor(obj: T) { 
    this.obj = obj; 
  }
}

const dc: Container<Date> =
     new Container(new Date());

let o: ?string = null;

type U = number | string;

type BinaryTree =
  { kind: "leaf", value: number } |
  { kind: "branch", 
        left: BinaryTree, 
        right: BinaryTree }

type I = {foo: number} & {bar: number};

let y: I = {foo: 1, bar: 2};