Add Scala Lang

[Velythyl]

Here's the language's website https://www.scala-lang.org/

[FlorianCassayre]

Note that as for Python there are two major Scala versions (2 and 3); but unlike Python the newer one is very recent (less than two years old). Since Scala 3 is still evolving very quickly, if we were to add this language I think it would be best to rely on version 2 which is actively maintained but will not benefit from any new language features.

[Steffan153]

I'd add Scala 3. It's been around for enough time (imo) that it's plenty stable enough.

However, we have the same problem as Kotlin: It takes >=5s to run a program.

[FlorianCassayre]

Scastie, the official Scala sandbox running on the web, have managed to do it for both versions (<1s on a cold start). We should study how they did it and decide how to proceed (source code).

[Steffan153]

Interesting. This is what I get on my machine:

[FlorianCassayre]

Yes, this is to be expected on a "regular" environment. Part of that time is spent compiling the code, and the other part starting up the program (slowed down by the standard library).

[Velythyl]

The issue is also that on a local machine, the programs run on the JVM, which tends to be very bloated and slow to boot up

[FlorianCassayre]

Unless I am mistaken I don't think the JVM is the main issue. According to Scastie:

We run your code in an isolated Java Virtual Machine on our servers.

I am currently checking how they implement this "isolated JVM".

[Steffan153]

Here's what I get on a fresh Alpine image. No extra junk and bloat installed, just JRE and Scala.

Would it be faster to use sbt?

[Steffan153]

I was looking into this and noticed that even on Scastie, it's technically slow, because on the first run, it starts up sbt and takes over 5 seconds. On subsequent runs, it's fast because it uses the same running sbt instance.

[FlorianCassayre]

I was looking into this and noticed that even on Scastie, it's technically slow, because on the first run, it starts up sbt and takes over 5 seconds. On subsequent runs, it's fast because it uses the same running sbt instance.

Is it?
I tried loading the page in incognito mode and quickly executing a script and I didn't notice any delay. Perhaps they are preloading sbt instances in a pool and then use them as they are requested by the clients? Or could they be sharing instances between clients?

[Steffan153]

I don't know but I've tried several times and on each load, it takes a while to start up.

Using Scala 2 is quite a bit faster though.

[frankchoongsaeng]

Maybe ditch sbt and use ammonite instead. I've used this a few times and I think it'll be perfect for this usecase