適当にflowの練習

tekitoru_flow.js

/* @flow */

function p(w: string) {
  return new Promise(resolve => {
    setTimeout(() => {
      resolve(w);
    }, 100);
  });
}

p.then((resp: string) => {
  console.log(`${resp} is returned!`);
})

type Obj = {
  a: string,
  b: number,
  c?: boolean
}

const myObj: Obj = {
  a: "hoge",
  b: 1,
  c: true
}

const arr: Array<string> = ["a"];

interface Callable {
  say(string): string;
}

class Hoge implements Callable {
	say(w: string): string {
    	return `${w} retured!`;
    }
}

const hoge : Hoge = new Hoge;
hoge.say("test");

interface CallableGenerics<T> {
	say(T):T;
}

class Foo implements CallableGenerics<string> {
	say(w: string): string {
	  return w;
    }
}

const foo: Foo = new Foo;
foo.say("test generics");

function unionFunc(v: number | string | boolean): string {
  return String(v)
}