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Comment by dtech | Hacker News Reader

I left the Scala ecosystems (mostly) a year or 4 ago, right around the release of Scala 3. It's a shame that the compatibility and tooling situation doesn't seem to have improved much since then. The Scala devs always said they wanted to avoid a Python 2->3 situation, but it seemed like they didn't quite achieve that.

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I think you should read this report. They made heavy use of many advanced features of Scala 2. Few codebases look like this (and very, very few need to) yet they were able to do it.

Moreover, they didn't need to do it. What makes it similar to the Python 2 -> 3 situation is the lack of urgency to migrate, because nobody suffers for not migrating. That's a good thing.

Most people used advanced features, even if they were hidden behind libraries. Even if you’ve just had a codebase which only used playframework.

If they are in libraries it doesn't matter, because you can use Scala 2.13 code in Scala 3.

It definitely took a while for most libraries to catch-up with Scala 3, now, I don't see anything is missing in the main area I work with (web development), playframework already works for Scala 3.

The article mentions they used an experimental language feature, which is enabled via a special compilation flag and came with a big warning from the start that it was in fact experimental and could be removed any time. I highly doubt that most people use any libraries that use those.

As a side note, I've personally had the experience of migrating several projects to Scala3 (when it was still called Dotty), and never had any issues with 3rd party dependencies, since Scala 3 is binary-backwards compatible with Scala 2.13

i was surprised to see such advanced type features. i worked at a large scala company. we wouldn’t let most of this stuff through code review. it generally is the kind of magic that saves a tiny amount of code at a high cost of complexity. sounds like this was the authors pet project and wanted to explore instead of write maintainable code

I don't know, if anything the Scala situation seems much worse than the Python situation. The language looks completely different and there is no easy migration path (not that Python had one, but at least the language was almost the same and you could with some effort write code that worked in both versions).

We are in Scala 2.13 and while there are talks about migrating there is no actual plan. Looking at this blog post the situation seems to be more dire than I initially expected. I think we will only end up migrating when the situation becomes unsustainable (libraries stop supporting Scala 2).

Odersky forcing through major syntax changes for Scala 3 was such an unforced error. It's baffling add new syntax on top of major semantic changes to the type system.

But did it provide a gain in power and soundness? There issues with the 2.x system.

Most programming languages have unsound features.

It did, which makes it all the more frustrating that you can't adopt it separately from the syntax and tooling changes.

But the new syntax is optional, right? So you could upgrade and keep the old syntax? (I'm not a Scala dev, so this is just my impression.)

Some of the syntax changes are optional, some of them like the _/* change aren't.

Stroustrup said "There's two kinds of PLs, ones that people complain about and ones that nobody uses."

Odersky made Scala3 become a language that nobody uses and people complain about!

Problem is he’s a full time academic.

So he doesn’t care if this amazing feature he’s invented has no IDE support.

Or if the Scala tooling ecosystem is so ridiculously poor.

I don’t use Scala but it will always be better than Python 2/3 because of compile time type checks. If it compiles it should work. In the case of Python 2/3 you could often encounter upgrade issues during runtime !

That can happen in Scala as well because of shared binaries, as is reported in this thread.

It’s a completely different situation compared to Python.

With Scala 2.13/Scala 3 they both compile down to an intermediate format called TASTy which allows binary code to be shared. You don’t get the same binary incompatibilities you do with other languages.

That is why I said it “should” work. There are always some really weird edge cases. My broader point holds true. Scala upgrade is not even close to Python 2/3 debacle

Python had 2to3 and 3to2.

While the tooling isn't perfect, it has improved considerably over the last years, I remember when IntelliJ couldn't deal with Scala 3 but now, it rarely complains.

Related to Python 2->3, I don't see how Scala 2->3 compares, there are clear migration guides + tools to help re-writing to switch between the new/old syntax, I have done many migrations and I have used these tools since the time when Scala 3 was launched (I admit that I reverted a migration at that time).

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