scala-js/scala-js

Scala.js, the Scala to JavaScript compiler

Objektwerks

@objektwerks

@yurique:nowhere.chat Thanks!

August Nagro

@AugustNagro

Wonder if it would be worthwhile to replace js.UndefOr with Scala 3 union + extension methods:

extension [A] (a: A | Unit)

  def isEmpty: Boolean =
    a == ()

  def isDefined: Boolean =
    !a.isEmpty

  def map[B](f: A => B): B | Unit =
    if a.isEmpty then () else f(a.forceGet)

// etc

@main def main(): Unit =
  val a: Int | Unit = 21
  println(a.isDefined)
  println(a.isEmpty)
  println(a.map(_ + 1))

Doesn't seem possible w/ Null union unfortunately.

Sébastien Doeraene

@sjrd

js.UndefOr is a Scala 3 union + extension methods in Scala 3 (well, implicit conversion to value class, but all the same).

Martijn

@martijnhoekstra:matrix.org

[m]

I have a cargo-culted scalaJSLinkerConfig.withBatchMode(true). What does this do/change

Sébastien Doeraene

@sjrd

It prevents the linker from using its incremental mode.

That encourages it to release memory sooner, which is sometimes useful in a CI context.

But in a dev context, it's likely slowing you down.

Martijn

@martijnhoekstra:matrix.org

[m]

Ah, thanks

Objektwerks

@objektwerks

With scalajs 1.5, in a crossproject, using fullOptJS/fullLinkJS, is the former sharedjs-opt.js merged into js-opt.js? Using fastOptJS/fastLinkJS separate main.js files, in js and shared subprojects, are generated.

Sébastien Doeraene

@sjrd

@objektwerks Could you elaborate? There's no such thing as a "shared subproject" when just using a cross project. A cross project is only sugar for two projects: a JVM one and a JS one. There's a shared source directory, but no shared project.

Objektwerks

@objektwerks

@sjrd I've always used a shared subproject to share .js and .jvm js and classes between the js and jvm projects. Did that change recently? Here's an example project: github.com/objektwerks/scalajs.pool. Some time ago, js-opt.js and shared-opt.js files were generated from a fullOptJS. That has changed with 1.5 and the module linking feature.

Objektwerks

@objektwerks

I guess I've always viewed the shared crossproject as another subproject. That said, I was just curious why the shared/.js shared-opt.js file is now empty after a fullOptJS/fullLinkJS. Hence the merge shared/.js into js/js-opt.js question.

Sébastien Doeraene

@sjrd

If you have a non leaf project, its JS files are empty (except for boilerplate), and so calling any of the linking methods on them is useless.

This has always been true.

It's just that maybe because of aggregation, you were calling linking methods of the shared stuff without actually meaning to?

Objektwerks

@objektwerks

Ok. Because I used to specific both js files in my index.html file. So is ALL of the generated JS being placed in the js/js-sbt.js file?

Sébastien Doeraene

@sjrd

Yes.

There was never any reason for you to include both JS files in your html. The shared one contributed nothing useful.

Objektwerks

@objektwerks

Ok, great. I was thinking that - but wasn't sure. :) Thanks, Sebastien! Cheers!

Sébastien Doeraene

@sjrd

Graag gedaan.

Objektwerks

@objektwerks

Dutch, eh? Nice.

Sébastien Doeraene

@sjrd

I'm Belgian so I speak some Dutch, yes.

Joel Moberg

@joelmo

"starting from 45kB gzipped for a full application." 45kB gzipped is heavy but maybe alot of libraries are included? In haxe I can create libraries that start from ~7kB gz then I have IO function and http client and some more.

It's also before minified..

Sébastien Doeraene

@sjrd

I'm afraid the 45 KB don't include much of libraries. It's, unfortunately, mostly the Scala collections. It's the price to pay to get full Scala.

Haxe plays a different game.

Joel Moberg

@joelmo

I will stay with have then. Thanks for answering.

Objektwerks

@objektwerks

How can I modify the fast/fullLinkJS output directory name. For instance, in lieu of js-opt or js-fastopt, I might want to name both js for the sake of consistency. I've attempted to set scalaJSLinkerOutputDirectory, but with no success.

Sébastien Doeraene

@sjrd

It's that setting, but it needs to be scoped in Compile / or Test /

Objektwerks

@objektwerks

Ok, let me try that.

Sébastien Doeraene

@sjrd

That said, if you make both fastOpt and fullOpt point to the same location, you'll confuse sbt's change detection mechanisms, and things can go wrong (either recomputing things too often or not often enough).

Objektwerks

@objektwerks

Ok. I've tried this fastLinkJS / scalaJSLinkerOutputDirectory := file("js") with no success.

Sébastien Doeraene

@sjrd

Compile / fastLinkJS / scalaJSLinkerOutputDirectory := file("js")

Objektwerks

@objektwerks

Ok. I got this to work Compile / fastLinkJS / scalaJSLinkerOutputDirectory := target.value / public / "dev" I tried you way, but the linker got a bit lost in terms of directory location. All I can say is - sbt is an art. :)

Sébastien Doeraene

@sjrd

Once you learn to use show, inspect and above all inspect tree, a lot of things become much easier.

Objektwerks

@objektwerks

Ok, thanks for the tip, Sebastien!

Sébastien Doeraene

@sjrd

For example, inspect proj/fastLinkJS directly tells you that it depends on proj / Compile / fastLinkJS / scalaJSLinkerOutputDirectory, among other things.

Objektwerks

@objektwerks

@sjrd Yeah, sbt inspect and show provide a bit of info.:)

Carlos Quiroz

@cquiroz

Finally got around to use dynamic ES imports with scala.js

Works great, thanks @sjrd and the team for this awesome feature

Sébastien Doeraene

@sjrd

It's mostly @gzm0 in this case 😉

Martijn

@martijnhoekstra:matrix.org

[m]

Is there a way to get a stack trace from a running scalajs program on node a la jstack?
I see there is a way to connect a debugger, maybe that's a fruity approach. Is there anything already there in any of the usual tooling for attaching debuggers (maybe even with sourcemaps)?

Naftoli Gugenheim

@nafg

Is there a benefit of sbt-crossproject over sbt-projectmatrix?

Sébastien Doeraene

@sjrd

sbt-projectmatrix is a generalization of sbt-crossproject.

That said, it creates even more projects in the build, so it can slow it down.

Naftoli Gugenheim

@nafg

@sjrd is that true even for only one scala version, or do you mean that it creates a project per scala version?

Do you mean it slows it down by taking longer to load the build (more settings for sbt to process), or that if it's compiling two scala versions in parallel that can be slower than just one (but still might be faster than compiling the same scala versions via ++)

Sébastien Doeraene

@sjrd

It creates one project per Scala version, yes. It's typically pointless to use project matrix if you don't have multiple Scala versions.

And yes it makes the build slower to load.

Naftoli Gugenheim

@nafg

That's sbt's major issue still, it seems to be slowed by the huge number of settings it proliferates. And Mill still doesn't seem to have enough plugins for me to switch to it

Where communities thrive

People

Repo info

Activity