Scala-js v0.3 released | Hacker News Reader

Scala-js v0.3 released

github.com

68 pointsiamtechaddict11 comments

Scala-JS has been making very fast progress lately, the 0.1 release wasn't that long ago. I'm excited to see where it goes and I think there's room for some very cool integrations with Play.

akka (Actor System) too, sjrd is working on it

Akka code written in Scala compiling to Javascript??

I think this is it https://github.com/sjrd/scala-js-actors

With no intention of downplaying it, but I think the biggest "blocker" is the resulting file size, making it unfeasible for production.

Doesn't advanced compilation cover that case?

The "Hello World" example is over 80Mb after compilation.

We've managed to get a hello world app down to about 300kb; most of that is the standard library, and even a several-1000-LOC game like [roll](http://lihaoyi.github.io/roll/) clocks in at about 340kb. Getting this number down is WIP.

The title mentions Futures & Promises, but the link is directly to the GitHub project without any further information about those concurrency constructs.

I'm curious if they managed to implement the blocking operations of Future [1], such as the "result" method. And, if so, did they accomplish that using the same Continuation Passing Style transform that Scala's Delimited Continuations [2] plugin uses, or some other means?

[1]: http://www.scala-lang.org/files/archive/nightly/docs/library...

[2]: http://www.scala-lang.org/api/current/index.html#scala.util....

It uses normal Scala `Future`s. You get two `ExecutionContext`s: `queued` and `runNow`. You can't block on a `Future`. That covers just about all the ScalaJS specific stuff, the rest is plain Scala.

Take a look at [Scala.Rx](https://github.com/lihaoyi/scala.rx) or [uTest](https://github.com/lihaoyi/utest) if you want to see code examples of how `Future`s are used in ScalaJS, but I think you'll be disappointed: it's exactly the same code that gets run on Scala-JVM!

You said:

> You can't block on a `Future`

Which answers my question. Thank you.

But then you also said:

> it's exactly the same code that gets run on Scala-JVM

That can't be exactly true, since "Awaitable" [1] doesn't appear anywhere in the scala-js codebase. So I guess as long as you don't mention that trait by name, or attempt to block on a future, then your effectively duck-typed Scala-JVM code will be able to run unmodified on Scala-JS.

[1]: http://www.scala-lang.org/files/archive/nightly/docs/library...

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