Announcing TypeScript 2.1

Post by jtmarmon » Wed, Dec 07, 2016, 7:58 PM UTC

virtualwhys wrote: post #109

jtmarmon wrote: post #83

Can someone comment on the difference in reliability between using typescript and a natively statically typed language like haskell or scala? Is there any? Or is the type safety really as good when you use ts

They're different things, TS is a transpiler while Haskell (GHCJS) and Scala (Scala.js) compile respective host languages to javascript. In a perfect world you'd go with the latter, but there's overhead involved (relatively slow compilation and large generated binaries) that is mostly absent in TS. Also worth noting that TS' community is gigantic in comparison to that of Scala.js and GHCJS.

Post by thejameskyle » Wed, Dec 07, 2016, 8:03 PM UTC

wereHamster wrote: post #70

Vekz wrote: post #57

Earlier quoted context omitted.

Its true and unfortunate. Typescript is the new Coffeescript. It splits the ecosystem. Flow is a progressive enhancement and improves the ecosystem. Typescript has had more push in the mindshare marketing from Microsoft.

TypeScript doesn't split the community any more than Flow does. TypeScript remains very close to ES2016/2017, syntax-wise, with the only major difference being type annotations, but you have those with flow as well. Anybody who can read JavaScript can read TypeScript.

    function foo(val /* : boolean */) /* : string */ {}

Post by thejameskyle » Wed, Dec 07, 2016, 8:09 PM UTC

edblarney wrote: post #101

Dear TS authors: Thank you (!) for your amazing contributions. TS is the best new thing in tech. That said: Your linguistic genius is way ahead of the tooling. I feel as though some of these 'new and cool' 2.1 things are a little bit intellectual, maybe useful in some cases ... But getting TS to work in the real world, the various build configurations, tool-chains etc. - it's still clumsy. It was difficult to grasp t…

Post by jauco » Wed, Dec 07, 2016, 8:20 PM UTC

seattle_spring wrote: post #32

icholy wrote: post #26

Earlier quoted context omitted.

The new type system features are: keyof, lookup types, and mapped types. Does flow have even one of these?

$Keys for keyof, $MapObj for mapped types. They are sorely missing lookup types though.

Post by billti » Wed, Dec 07, 2016, 8:21 PM UTC

ggregoire wrote: post #40

timruffles wrote: post #11

If you still haven't given TypeScript a go as a Javascripter, now is a great time to do so. Whether you end up adopting it or not, it's interesting to get the types out of your mind and into the code. The first time you feel the speed/confidence of refactoring with accurate 'Find usages', you'll decide if the undeniable overhead of types is worth it.

> The first time you feel the speed/confidence of refactoring with accurate 'Find usages', you'll decide if the undeniable overhead of types is worth it. For your information: in VSCode, the "Find all references" and "Rename symbol" work out-of-the-box, even if your code isn't typed. Edit and disclaimer: Not sure why I'm getting downvoted, my comment doesn't contradict parent message. I personally type my code too (w…

  ```javascript
  var foo = {
    a: true, // Find all references on "a" here...
    b: "hello"
  };

  foo.a = false;
  bar(foo);

  function bar(obj) {
    obj.a = false; // Won't find this "a".
  }

  ```

  ```typescript
  interface Foo {
    a: boolean;
    b: string;
  };

  var foo: Foo = {
    a: true,   // Find all references on "a" here...
    b: "hello"
  };

  foo.a = false;
  bar(foo);

  function bar(obj: Foo) {
    obj.a = false; // Will be found, renamed if refactored, etc..
  }

  ```

  ```javascript
  /** @typedef {{a: boolean, b: string}} Foo */

  /** @type {Foo} */
  var foo = {
    b: "hello"
  };

  foo.a = false; // Find all refs here
  bar(foo);

  /**
   * @param {Foo} obj - Some object
   */
  function bar(obj) {
    obj.a = false; // will find this one
  }

  ```