Scala 3 Migration: Report from the field

I double that. Rust is great language, and I like it a lot. But usually I pick Scala whenever I can, it’s perfectly suited for complex domain.

So my rule of thumb is: Large enterprise monolithic projects - Scala. Microservises, serverless functions, systems where resources have hard constraints, cli apps - Rust.

Both are great languages.

Hmm. Fair point for Rails and Laravel (whereas I think React had a killer app in terms of being able to make SPAs without going crazy) but those are tools that you can pick up for a one-off throwaway project - indeed I suspect most adopters didn't "move" to them so much as start doing projects in them and eventually stop doing projects in other things. Scala was never really competing in that space - I don't think anyone would ever say "let's make our website for the next tradeshow in Play" - it's a "heavy" language that needs an IDE and deep familiarity to get the best out of it (and partly that's also what JVM folks would be expecting). So it needed to play for the big core codebases, and for a while it did (particularly when there was no alternative to Spark).

Could they have made Play an alternative to Rails for one-off throwaway websites? Maybe, but the thing that would have needed to be different wouldn't be pushing Play itself, but rather lighter tooling and making it easier to get from zero to pages being served. Honestly I struggle to see how they could've done it without making the compiler and build tool much faster, and either making the IDEs much more efficient (difficult) or making the language easier without an IDE (difficult, and would risk splitting efforts). And even then, you wouldn't really show the compelling advantage of Scala, which is fearless refactoring in large codebases. I don't know that it could ever have been better than Rails at what Rails does, and also we already have Rails. Whereas even if it eventually "dies", Scala has already pushed Java and Kotlin to be much better than they were.

I use Play, and I think it is a good web framework, nowadays.

In the past, however, upgrading to new versions, was annoying, because of pretty big changes in the API. (Don't know if this is what GP had in mind though.)

And even worse (I suppose) for people who were using the different ORMs which have come and gone, instead of plain SQL.

Akka has been annoying too: Adding WebSocket to my project, using Akka, was extremely much more complicated than doing the same in Nodejs (at least looking at the Nodejs docs I've seen).

Today, to me, Play is feature complete and all I want is maintenance updates (and performance optimizations but not so important). And yes, that's how things look right now: Some bigger companies pay an open-source maintainer, so Play gets regular maintenance updates, but not any annoying major API changes (or so I hope), nice.

Play has become boring in a good way? :- ) (Thinking about some "Use boring tech" HN posts.)

Like KajMagnus mentioned:

- The churn caused by breaking changes in minor versions used to be annoyingly high.

- Slick looks neat at first but caused a lot of friction when used by less experienced developers.

- The fact Akka is in your dependency tree encourages people to reach for it and raw actors are usually a bad choice. Akka streams work well for websockets and SSE but it's another footgun.

Additionally:

- It was in state of semi-abandonment for several years before Lightbend gave the project to the community. Even though there are/were big companies deploying Play apps at scale, for instance Apple.

- The introduction of Guice (in 2.4 afaik) was a terrible mistake, completely unnecessary and at odds with the Scala philosophy. Sure you can not use it, or use something else (like macwire) but defaults matter.

- Play-JSON depends on Jackson which is annoying in the JVM world, causing binary compatibility issues when you have diamond dependencies.

- Standard library Futures are not so nice when you've experienced anything else (Scalaz Task, Cats IO, ZIO, even Twitter Future...)

- Code generation from routes files is an odd choice when Scala has always been expressive and DSL friendly.

- Swagger/OpenAPI integration is brittle.

I've personally used Tapir since 2019 and couldn't be happier. All Play apps still running at my company are being abandoned or replaced by Spring/Java projects.

Scala has some nice and cool vibes and features to it.

But that is where good parts end.

From the POV of real world boots-on-theground software challenges and developers it is a poorly designed, overengineered and overrated piece of complexity.

Complexity disconnected from reality of software engineering as a tool to serve business needs.

I can explain why this happens but I don’t want to get downvotes. People hate hearing bitter truth:)