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Comment by pcx | Hacker News Reader

Associated functions and associated constants sound so yum! That's one thing I would love to have in Flowtype. But classes seem to serve that use case well enough.

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You get something similar to with static methods and properties on class definitions. In plain ES2017-ish class syntax:

class Test {

  static value = 1;

  static someStaticMethod = () => {
    return 5;
  }

}

console.log(Test.value) // 1

console.log(Test.someStaticMethod()) // 5

Edit: Sorry, this actually a Stage 3 TC39 feature. Not sure if you can use it with flowtype (I think you can), but you might be able to if you enable babel with stage-3 features:

https://github.com/tc39/proposal-class-fields

You don't actually need this fancy class syntax anyway. You can just define a class and then do:

Test.value = 5

Test.someStaticMethod = () => { return 5; }

The class stuff is just sugar over the prototype stuff anyway, and a class is just a constructor function object with a prototype chain.

Yeah, either way it is objects. Traits feel so much more flexible though; and more natural a layer over JS object-orientedness. It also makes it a pain that there are some important semantics missing while using classes in JS. Someitmes Java feels much better.

The real problem is that ES classes map onto a paradigm of prototypal inheritance rather than traditional inheritance (as in Java). The discrepancies between the two cause a leaky abstraction, like how a class still has a prototype chain, for example.

Note, I think in spite of being in stage 3 the syntax and obvious cases seem to be largely unlikely to change. It certainly improves react quite a bit: you can define the proptypes and default values inside the class rather than after.

> Associated functions and associated constants sound so yum!

In the simple (not trait) case they just seem to be the same as "public static" constants and functions in C#, java etc.

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