Ideas on type hinting and named parameters

Andrea Giammarchi andrea.giammarchi at
Tue Jun 9 08:57:59 UTC 2015

quick personal thoughts on this matter, leaving the named arguments part
beside (as it is looks kinda redundant/unnecessary effort that could wait)

We've been talking about types for long time in here and the good old
direction was *binary data* in the form of `StructType`

const Point2D = new StructType({x:uint32, y:uint32});

let xy = new Point2D({
  x: 0,
  y: 0


Not only this option looks and feel more consistent with typed options we
have already in core such `Int32Array` and others, but it will be way
easier to gracefully migrate to such new pattern and fully, or partially,
polyfill for older engines.

Back to typed Array, I think this:
var xyz = new Int32Array([1, 2, 3]);

is better than:
var xyz = [
  int32 = 1,
  int32 = 2,
  int32 = 3
or whatever repeated operation we could have per each `xyz` like variable
of "that kind", so whatever would eventually work as StructType might be in
my opinion more suitable.

  1. you recognize upfront what kind of duck you are working with
  2. you define such type once instead of each time, reducing errors/typos
  3. when you pass data around you can specify as example just `Point2D`
instead of `Array<T Int32>` and friends that are imo not so nice to have in
a scripting language
  4. we have already tools capable of bringing in types in similar fashion
you proposed ... how about we do something better than some syntax tools
friendly, instead of some syntax optimized for developers?

Moreover about classes, you have defined properties that AFAIK are not
allowed by current specs. ES6 classes accepts only methods and/or getters
and setters so I'm not sure properties should be discussed together with
types, maybe worth waiting for better understanding on how properties will

That being said, I see why you used space instead of colon, and for literal
objects that indeed looks like a better approach.

Best Regards

On Tue, Jun 9, 2015 at 5:19 AM, Luke Scott <luke at> wrote:

>  Hello All,
>  I wanted to share some ideas with you for type hinting:
>  I’m also putting this together for named parameters:
>  The two are somewhat related. The type hinting doc uses white-space
> instead of a colon. And in the named-arguments doc a colon is used for
> named arguments.
>  I realize that there may be some strong opinions on a colon vs
> white-space. Using white-space instead is an attempt to be compatible with
> existing ES syntax (POJO uses colon already), while allowing for other new
> features, such as named parameters.
>  Looking for feedback and any interest on any of the above.
>  Luke
> _______________________________________________
> es-discuss mailing list
> es-discuss at
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <>

More information about the es-discuss mailing list