Scala was the second programming language I learned (the first was Java). I think I'm quite lucky to have picked up a language like Scala so early in my programming journey. It made it very easy for me to learn new programming languages, since it made it easy to support wildly different paradigms (which is also what makes it hard to use in an enterprise environment).
yeah, you get everything and the kitchen sink with Scala. Which is actually IMO its biggest weakness. It wants to be everything, and it isn't amazing at anything as a result.
That is why I actually like Scala. I want every tool to be available at my disposal, and I can choose what to use or not use. I want it to be reasonably succinct and type safe.
I don't want the language to dictate how I use it. I'd prefer the language not to look out for me. There might be some, but a lot of languages look out way too much. Golang for example doesn't allow you to compile if there is an unused var. Java with private as the default.
It is great that there is a production-ready language that differs from other languages.
Python is multi paradigm, but does several things really well that other ecosystems do not. Javascript as well. Java as well. What claim to fame does Scala have in this regard, aside from being the best supported language for Spark for several years before PySpark overtook it? Perhaps Akka before the boneheaded decision to paywall that ecosystem?
>> Every significant language became multi-paradigm these days, but you can do it intentionally, like Scala, or you can do it badly.
> Python is multi paradigm, but does several things really well that other ecosystems do not.
Both Perl and Ruby can be, and often are, used instead of Python to great success for similar concerns. IOW, the three are often Liskov substitutable[0].
> Javascript as well.
You're kidding, right?
> What claim to fame does Scala have in this regard ...
Scala supports declarative, generative, imperative, meta, and object-oriented paradigms. All of which are supported by at least, but not limited to, the JVM and JavaScript runtimes.
These capabilities transcend libraries (such as Akka) and/or frameworks (such as Spark).
"Among the clients of the Spark runtime architecture, Scala is the most popular language, followed by Python and Java. According to a recent survey by Databricks, the company behind Apache Spark, 71% of respondents reported using Scala for Spark development, while Python was used by 24% and Java by 5%.
Another survey by Typesafe on the Spark ecosystem revealed that 88% of respondents used Scala, 44% used Java, and 22% used Python, with the percentages reflecting multiple language usage.
Scala is considered the most optimized language for Spark due to its integration with the JVM and its role as the language in which Spark was internally implemented, offering better performance and access to the latest features."
I think the info is even more outdated than that. The article is from August 2024 but it cites "a recent survey by Databricks" that from what I can tell isn't linked to, so who knows what data they're referring to.
I was deep into the big data ecosystem in the 2010s. Those numbers feel like they're from 2017 or so. Scala has been on a slide every since.
It's interesting that Odersky started with Modula-2 (implementing a Z80 compiler), did a PhD with Wirth, but there discovered that functional programming offered a level of theoretical rigor and mathematical elegance he missed in Wirth's imperative languages. Wirth was generally critical of the complexity and abstraction often associated with functional languages. Rather than rejecting Wirth's pragmatism, he carried it forward by attempting to make functional programming "industry-ready".
I can relate to Odersky, similar to him, while I appreciate Niklaus Wirth's work, I don't appreciate the quest to minimalism that he went down after Oberon.
For me the right path is Oberon => Oberon-2 and Component Pascal => Zonnon and Active Oberon.
Yes, I know he wasn't directly evolved with those ones.
I see the several revisions of Oberon-07 as an entertaining exercise in minimalism, which fails to understand the industry.
Something that Niklaus Wirth complained about in his rant about Software Engineering, not understanding why Java and C++ and not Oberon won the hearts of companies.
I was fortunate to attend his Oberon session on Oberon Day at CERN, 20 years ago, while a genius programming language designer, expecting software engineers to recognise great design and naturally embracing it, was expecting too much.
Minimalism is indeed the correct term (usually framed as simplicity) when looking at both, language and documentation. But at least it helped that there was always a working compiler and system, not a mere theory.
> I see the several revisions of Oberon-07 as an entertaining exercise in minimalism, which fails to understand the industry.
His main motivation was to minimize the amount of work porting his original system to his own, FPGA based processor board. His fans interpreted the “new” language more as a new prophetic proclamation, but in reality it was only about the feasibility of his post-retirement hobby project. This became clear at the latest when people wanted to run a benchmark on the system and discovered that the compiler couldn’t generate such large binaries. There was simply a fixed maximum size, but for many years no one noticed this.
He has always positioned his languages for education and limited himself to the systems that can be realized with them. If his goal had been to meet the needs of industry, he would have acted differently. After a very brief foray to an industrial job in the sixties, he immediately returned to academia and hardly looked back.
One could argue that Modula-2 was an attempt to fix Pascal for the industry, after all the dialects that sprung out of it, which he wasn't keen on, with the influence from Mesa, after his sabbatical at Xerox.
Also that the way it failed to be embraced by the industry, too busy with UNIX, C and C++, also had an effect on his point of view going forward.
> One could argue that Modula-2 was an attempt to fix Pascal for the industry
There is no evidence that Wirth e.g. ever directly or specifically rebutted Kernighan's famous paper, nor that Modula-2 was a response to it. Modula-2 was a child of the ivory tower (PARC), not industry. Wirth was rather an "escapist" who built his own worlds rather than fixing the real one. He saw Parnas' concepts "in action" during his sabbatical at Xerox. He didn't create Modula-2 to help industry; he created it because he wanted to replicate the Alto workstation experience (which became the Lilith) for his own use and for his students at ETH. Wirth was a brilliant "synthesizer" of academic ideas (Parnas, Hoare, Mesa) who built beautiful, self-contained gardens for himself and his students. He was never the "industrial repairman" that later apologists tried to paint him as.
That paper was only relevant among UNIX people, and largely ignored by anyone doing 8 and 16 bit home computing with Pascal and Modula-2.
It is no accident that to this day, it is the UNIX accolades that keep bringing it back every couple of months, most of whom never used a single Pascal compiler in their lifes, or aware that Modula-2 was already around.
Modula-2 relevance as systems language is quite easy to find out in some of his essays, and the companies selling compilers for Acorn, Amiga and PC.
You said that "One could argue that Modula-2 was an attempt to fix Pascal for the industry". By 1981, the C/Unix team was no longer a "rogue research group" in a closet; they were the architects of the dominant industrial paradigm shift (with Apollo Computer, Sun Microsystems, Silicon Graphics, and even Microsoft all using Unix and C). That's why I mentioned it. Wirth didn't care because his concern wasn't industry. Pascal users helped themselves: e.g. Lisa Pascal essentially included all features from C Kernighan (who refered to Wirth's original Pascal, not the derivatives) was missing and even a module and separate compilation concept (four years before Turbo Pascal); they could have used Modula-2, which was around at the time. While Modula-2 was hypothetically a "systems language", it lacked the pragmatic "dirty" features that C, Lisa Pascal, and Turbo Pascal embraced to actually build operating systems and drivers on commodity hardware (unless, again, they were added as an extension by the compiler vendors). E.g. Topspeed Modula supported inline assembly, Acorn Modula included extensions to call software interrupts directly with register mapping; almost all commercial vendors added extensions to bypass strict typing, or direct pointer increment/decrement to support C-style array traversal.
It is irritating that apparently C is fine having endless compiler extensions without which ISO C is equally unusable to implement an operating system[0], a sign of greatness, while the same argument is used to point out as design flaws when it isn't C we are talking about.
[0] - Unless helped by an external assembler, just like on the UNIX rewrite, when K&R C was initially created.
It is, of course, well known – or at the very least frequently and enthusiastically repeated – that a suitably drunk Odersky devised Scala whilst watching a Reese’s Peanut Butter Cup ad[0].
Martin Odersky did a fantastic job with Scala then, and also with Scala 3 IMO from a language design perspective. When I first got into Scala, I was blown away by the language features and the type system. It was the reason I got back into the JVM and the reason for getting into functional programming (not pure FP).
Scala is a great language, and functional programming (not pure functional) made me a much better programmer. And functional error handling is a fantastic way to model success and failure, whether you’re using Either or the newer Result type.
I have to both agree and disagree with some of the commenters here regarding why scala declined in usage. There are several reasons.
1. People just got fed up with the push toward pure FP and the complexity. Pure FP and category theory, and effect libraries are just not for the average audience.
2. Android support for Kotlin drastically reduced the momentum as well
3. Spark usage was pretty heavy driver for using Scala and I’m not sure about it’s used as much.
4. Scala became more and more niche as a result of item 1 above.
This being said, I switched to Kotlin for all server side work. I think a language and in particular the ecosystem, needs the vision/stewardship that can offer more practicality and balance in the language design, programming style, tooling, and frameworks. Kotlin just became a simpler language with better support for all of the above.
I can’t think of a better company to drive the development than Jetbrains. I don’t agree with all the choices, but Kotlin overall is a beautiful, simpler language, with all the practicality, and support needed to keep it going.
However, now that Java is making strides in the language features, as compared to historical improvements at the VM level, I’m curious to see how the market share for Kotlin outside of android is going to be affected.
Personally, I still prefer Kotlin for the practical FP support, Ktor as an HTTP server, and pretty good compatibility with Java. And lastly, I think there is enormous potential in multiplatform, as a strong alternative to typescript/react native for mobile.
Disclosure: I am biased as I’m developing some libraries and soon to be made (more) public server framework.
> However, now that Java is making strides in the language features, as compared to historical improvements at the VM level, I’m curious to see how the market share for Kotlin outside of android is going to be affected.
My employer has decided to abandon Scala, and they proposed Java as the language to head toward. I don't think Java's strides are fast enough to provide modern table stakes. In 2025, the big ones to me are:
1. null handling at the cultural and language level
2. abstractions over concurrency
For null handling, Java has Option, but you're just going to have to deal with the fact that basically any API or caller can give you null. This is not good enough in 2025.
For concurrency, Java has an excellent java.util.concurrent package (and the JVM is very good at concurrency in general). However, I've come to believe that it's a losing proposition to expect the average programmer to use concurrency primitives correctly, even at that level of abstraction. Every Java PR I review I have to add 20-30 comments about thread interruption, memory barriers, etc.
Structured Concurrency helps, but is new/in preview, and hardly helps with actually providing safer concurrency operations.
I think Java is doing the right things and the glacial pace of innovation at the language level is correct for protecting their users (contrast this with Scala 3...), but on the flipside I just think that it is hard to recommend Java vs C#/Kotlin.
1. There was never a push. Functional ecosystems are simply the ones that survived. You can't blame communities that keep the language alive for doing what they want, and not what you want. Without Typelevel and ZIO where would be Scala 3's adoption today?
2. Android has never been even remotely relevant to the space where Scala exists. And no, this was not a missed opportunity for the language. People who think Scala had a shot are completely delusional.
3. I'm personally convinced Spark was the worst thing that happened to the ecosystem as it brought a lot of attention, and indeed, drove adoption, only to result in an incredible amount of shitty code plagued by the worst annoyances in the JVM and big data space. Spark is the biggest open source project in Scala, yet Databricks doesn't seem to give a damn about the language and couldn't even be bothered shipping a Scala 2.13 runtime for years after its release. I sincerely hope Spark moves away from the JVM entirely.
Kotlin is really not any simpler especially with the constant feature creep that results in copying Scala features, only halfbaked. It's even less principled which is the biggest gripe against Scala having too many ways to do the same thing. There's nothing beautiful or practical about a language where people regularly write expression oriented code next to early returns.
Given that Scala-Android efforts predate Kotlin, Scala could have had a shot at Android if EPFL resources were allocated to it, like to Scala.js.
Kotlin is not simple at all, it has a lot of keywords for strange and very specific features and corner cases, it's hard to remember them all. Moreover, the Intellij Kotlin plugin is somehow slower than Scala's despite being a 1st party language and not having implicits, how they managed to achieve that is a mystery.
Right and if you know the first thing about Scala, Kotlin, Google and JetBrains, it should be clear Scala on Android was simply never going to happen, even if Typesafe somehow managed to find extra millions in funding and could allocate dozens of people behind it.
It certainly would, had Google decided that would happen, and support the ongoing existing efforts from the community.
If you know anything about Google politics, you would know Kotlin only took off because of a couple of folks on the Android Tools team doing free advocacy for JetBrains.
In an alternative reality, if those same persons had been Scala heads, Jetpack Compose would be a Scala DSL today.
Scala was a bad fit for the Android runtime and the SDK. On a $200 Android phone with 2015 specs the performance aspect was definitely not a trivial argument against Scala; Kotlin has perfect interop with very little overhead, no conversions between collections (often slow and immutable in Scala), a nullability story that doesn't box everything in Option, ...
And most Googlers do not like clever languages with bad tooling, especially the ones working to productize languages and toolchains for Blaze and other internal tools.
You will never get me to say anything positive about the Kotlin advocates on Android team.
It isn't only Scala, it is using Java 7 samples to sell Kotlin, the original language for Android, still used for the large majority of Android tooling, where your argument fails flat.
They have begrudgingly being updating Java support, up to Java 17, when Java 25 is the latest LTS, because that great Kotlin interop with Java is useless when Android loses access to the Java ecosystem that keeps moving forward regardless of Android.
Some of them even don't have any ideas how out of date their Kotlin "improvements" over Java are out of date.
I'm not defending JetBrains or Google's decisions. But I don't see why anyone should try to rewrite history.
Scala had a decade head start. Many people at Google are aware of Scala, some being former LAMP students or staff. Google doesn't simply add a language to their small list of sanctioned toolchains.
Kotlin was specifically designed to win the politics argument, using technical merits: full interop, gradual adoption, low overhead, ability to target outdated Java bytecode efficiently (Kotlin used to inline lambdas for Java 6 bytecode for instance, while Scala boxed everything before invokedynamic). It doesn't matter whether one approach is objectively right or wrong, Kotlin fitted the bill and Scala did not. More importantly, Kotlin fitted the bill on Google's server side too!
Then of course JetBrains was tasked to replace the IDE with Android Studio, they could put dozens people backing Kotlin as a first-class Android language, until Google adopted it officially.
But even if Typesafe had somehow stumbled upon $100M in funding to do the same thing, it doesn't change the fact that Scala never had a chance.
Kotlin won Android on internal Google politics, zero technical merit.
Feel free to write another long reply on how Kotlin is somehow special, going to replace Java, while the first iteration of Kotlin Native was a failure with a broken design on its reference counting memory approach, and there is still no KVM to replace the JVM in sight, despite such greatness as pointed out in Android circles.
I haven't defended Kotlin's approach in any way, I don't know why you want to put words in my mouth.
However if you don't see why Kotlin was well positioned, while Scala was not, then you clearly don't know much about either language.
Technical merit is subjective, but different design decisions can precisely be made to win politics or not, and JetBrains made the right ones, first to convince people internally (who knew about Scala, you know), then Google, as they were fairly well aligned.
> People just got fed up with the push toward pure FP and the complexity. Pure FP and category theory
Amen. My eyes start to glaze over whenever I read about covariance.
It's one thing if a feature works because of category theory, but if you just "feel like arrays should be covariant", and then the actual category theorists come along and can't work with its limitations, maybe give it a miss.
Wanted to get into enterprise-level back-end development in 2025 and was really drawn to Scala, but ultimately learning C# or Kotlin seemed way more practical.
Have error messages improved? I remember trying it few years back but the error messages made it hard to debug. Is it due to use of JVM? Sorry for my lack of knowledge since I rarely program in JVM based languages.
Compiler error messages improved significantly with Scala 3. IIRC there was a dedicated effort with Scala 3 to improve error messages and make them more actionable. Scala 2 error messages improved somewhat over time, but can still be obtuse.
It was before this: It was never a huge community, but from very early on it was split thanks to some rather unfriendly, competitive personalities and very different goals. You didn't just use scala: you either ran scala with a Twitter stack, or a typesafe(now lightbend) stack, or a scalaz stack, or a cats stack, or a zip stack. And a lot of the people developing each stack didn't like each other. I've gotten to work with core contributors of multiple of those, and knowing that I wasn't a devotee of any stack led to hearing way to much complaining in pairing sessions about how The Others (TM) were slowing down the adoption of the language.
A language that is really popular can manage having 5 ways to do things, but a small community is just going to lose steam. And the fact is, all the ways work just fine in a vacuum, but you can't just get really mature tooling when everything is just so split.
Yeah, I think with a community as small as Scala's, you can't really afford:
a. fragmentation of the ecosystem
b. repeated shuttering/abandonment of some of the most popular options (Lift, Play, Akka)
c. splitting the language in two
The perception within and without my own employer (which heavily invests in Scala) swapped from "acceptable" to "this ecosystem is a dead-end and we need to get out" with the launch of Scala 3. It's possible they would have reached the same conclusion, but I don't think breaking every industry engineer's development tools for years is a good strategy.
I don't think it is a problem with Scala 3 itself. Scala 3 brought a lot of improvements, one of them is using semantic versioning. People used to complain a log about binary compatibility between versions in 2.x. Now it's here.
I think that the slow adoption of Scala 3 is mainly due to one of its most successful projects: Apache Spark. To this day, Spark only supports Scala 2.13 although Scala 3 has been around for years now. This is both disappointing and frustrating because a lot of people were introduced to Scala thanks to Apache Spark.
The language is actually really nice. The "we won't ship dotty as the next version of Scala, just kidding, here it is", the breakage of editors and IDEs that lasted for years, etc (aka, the WAY they did it) make migrating a poor value prop. If I have to suffer worse tools and pay the tax of fixing them/updating them, then for each system when I think it's time to migrate to Scala 3 I might think it's time to migrate off Scala entirely.
It's possible that nothing could have reversed their existing trend, but I think it's fair to say that smaller communities (as another poster mentioned) can't afford this level of friction. Have we not seen Perl->Raku? Python2-3?
Additionally, while almost all of Scala 3 is an improvement over 2, whitespace significance seems like an awful hill to die on. Most people who value that sort of syntax in domains where Scala has made any inroads are already on Python, and we're going to alienate many existing developers in the (vain) hope of increasing marketability?
What really obliterated Scala’s momentum was PySpark overtaking Scala Spark coming from Python’s foothold in Data Science, columnar data warehouses carving out a big chunk of the batch processing pie as well, and then the Akka licensing change.
The Enterprise ecosystem quickly withered away, and now only type level programming diehards remain.
I think realistically we're looking at a lot of causes (which is not surprising; it's rarely a singular thing). Scala 3's momentum may have already been negative but how Scala 3 landed represented a nail in the coffin for a lot of individuals, teams, and organizations.
Scala 3 really landed at a bad time as the hype behind Spark, Akka, Play had already weaned off. Typesafe was struggling financially, and didn't back Scala 3 then (that went to VirtusLab).
Typelevel and ZIO really put a lot of effort to release many libraries on day 1 despite the hurdles with the 3.0 release, because these communities are alive and healthy. Yet Odersky is on a small crusade against monadic effect systems, which discouraged a lot of good people. On top of that there are neverending feuds and US politics...
Akka's demise started before the license change. It's an incredible piece of software but as it turns out, not so many people need stateful cluster sharding. Modern cloud architecture and simpler streaming libraries have made the Akka toolkit irrelevant to many use cases.
You're right about Spark and the next logical step will be removing the JVM from the equation entirely, which is already ongoing (see Photon or Comet).
Why is that? I think they did a lot of things right. Offer automatic conversions, backwards and forwards compatibility from a sufficiently recent 12.x version.
I think mostly Kotlin being simpler and Java gaining features ate the lunch. Also, software like Akka and Spark becoming less prevalent hurt because they were big reasons for devs to learn the language. Not to mention the community drama.
The only bad thing was that it took quite long for Scala3 to become available leading to a lot of stagnation.
From my perspective the two biggest challenges of the Scala 3 migration were macros and poor tooling support.
Macros were an experimental Scala 2 feature, but were used all over the Scala ecosystem. Because they were considered experimental a good migration story for them was never developed. That lack of support stopped migration efforts dead in their tracks at our company for a long while. It just wasn't worth contributing simultaneous support for Scala 3 and Scala 2 macros to every third party dependency who used Scala 2 macros. That said, we did it for some and lived on a fork for others.
IDE support for Scala 3 was really rough when it first released. We checked in on it with every IntelliJ release for roughly 3 years before we decided it was far enough along. Prior to that it was rough enough that we froze migration efforts in order to keep the tooling usable enough for engineers to be productive.
> IDE support for Scala 3 was really rough when it first released. We checked in on it with every IntelliJ release for roughly 3 years before we decided it was far enough along. Prior to that it was rough enough that we froze migration efforts in order to keep the tooling usable enough for engineers to be productive.
Same story for us - about 3 years before Intellij was usable, even then not up to what it had been on Scala 2. We still only have 2 Scala 3 repos, out of about 30, for my team, and we're actually MORE adventurous than most other teams at the company!
Well, IJ experience for Scala 3 is still noticeably worse than for Scala 2. We're still cross-compiling our work projects, waiting until Scala 3 support in Intellij is good enough to switch.
As other posters mentioned, a lot of it is about lacking critical mass in the first place. Making such a dramatic change is a high-risk thing, and Scala didn't have enough of a lead at all to justify it.
> The only bad thing was that it took quite long for Scala3 to become available leading to a lot of stagnation.
Unfortunately this isn't the only bad thing. The language overall is definitely a nicer language (though I complain about the whitespace change elsewhere). The tooling was broken for years, which actually stalled our team's migration. How could I advocate for moving to Scala 3, just to send everybody's editors and IDEs back to the stone age?
I'm not arguing that they built bad technology, I'm arguing that they ignored the reality: the value prop of moving to Scala 3 vs... moving to something else, at that point, isn't that compelling.
I remember being a big fan of Scala, and before Scala 3 it was looking to me that Kotlin was becoming a big competitor. Could that be, or do I have my timeline wrong?
It competes in some ways and not in others. It does a pretty good job of providing similar benefits as many Scala ecosystems, but providing approachability over purity.
Kotlin becoming The Official Android Language helps it quite a bit, though the future gets interesting if Google successfully abandons the JVM entirely to rid themselves of Oracle. I'm skeptical that Kotlin targeting multiple runtimes is a winning proposition, but it certainly seems to be doing a better job than Scala Native (also Rust is probably the better choice than Scala Native for that kind of code anyway).
I was first a big fan of Scala, and while I still like it, I am now really into Kotlin.
I don't find it disappointing: I tend to consider that Scala was an inspiration for Kotlin. Maybe Kotlin won by being simpler, and definitely because of the tooling and community: being backed by JetBrains and Google helps.
For a long time, the tooling was very limited with Scala, which must have slowed its adoption, right?
Kotlin is pretty nice. I think the build tool in Scala being so esoteric didn't help with adoption; I remember avoiding Scala for a few years because dealing with sbt left a horrible taste in my mouth.
Scala CLI should have happened 5 years before, but honestly sbt has improved a lot, the DX is mostly fine since the 1.0 release and it's maintained plugin compatibility for 8+ years.
Gradle is worse on several dimensions, which didn't really hurt Kotlin's adoption, nor seems to fundamentally bother Android developers (ok, they have little choice here).
Can you elaborate on what you're referring to? I can see performance becoming a problem if you repeatedly chain non-optimisable (in bytecode) as excluding the in place operations I believe all ops re-allocate the collection.
Scala was the second programming language I learned (the first was Java). I think I'm quite lucky to have picked up a language like Scala so early in my programming journey. It made it very easy for me to learn new programming languages, since it made it easy to support wildly different paradigms (which is also what makes it hard to use in an enterprise environment).
yeah, you get everything and the kitchen sink with Scala. Which is actually IMO its biggest weakness. It wants to be everything, and it isn't amazing at anything as a result.
That is why I actually like Scala. I want every tool to be available at my disposal, and I can choose what to use or not use. I want it to be reasonably succinct and type safe.
I don't want the language to dictate how I use it. I'd prefer the language not to look out for me. There might be some, but a lot of languages look out way too much. Golang for example doesn't allow you to compile if there is an unused var. Java with private as the default.
It is great that there is a production-ready language that differs from other languages.
Every significant language became multi-paradigm these days, but you can do it intentionally, like Scala, or you can do it badly.
Python is multi paradigm, but does several things really well that other ecosystems do not. Javascript as well. Java as well. What claim to fame does Scala have in this regard, aside from being the best supported language for Spark for several years before PySpark overtook it? Perhaps Akka before the boneheaded decision to paywall that ecosystem?
One thing it clearly doesn't do well is performance.
>> Every significant language became multi-paradigm these days, but you can do it intentionally, like Scala, or you can do it badly.
> Python is multi paradigm, but does several things really well that other ecosystems do not.
Both Perl and Ruby can be, and often are, used instead of Python to great success for similar concerns. IOW, the three are often Liskov substitutable[0].
> Javascript as well.
You're kidding, right?
> What claim to fame does Scala have in this regard ...
Scala supports declarative, generative, imperative, meta, and object-oriented paradigms. All of which are supported by at least, but not limited to, the JVM and JavaScript runtimes.
These capabilities transcend libraries (such as Akka) and/or frameworks (such as Spark).
0 - https://en.wikipedia.org/wiki/Liskov_substitution_principle
"Among the clients of the Spark runtime architecture, Scala is the most popular language, followed by Python and Java. According to a recent survey by Databricks, the company behind Apache Spark, 71% of respondents reported using Scala for Spark development, while Python was used by 24% and Java by 5%. Another survey by Typesafe on the Spark ecosystem revealed that 88% of respondents used Scala, 44% used Java, and 22% used Python, with the percentages reflecting multiple language usage. Scala is considered the most optimized language for Spark due to its integration with the JVM and its role as the language in which Spark was internally implemented, offering better performance and access to the latest features."
When is this from? I would be shocked if in 2025 most Spark was being written in Scala
August 2024 -- so, dated.. mea culpa https://moldstud.com/articles/p-what-programming-languages-a...
I think the info is even more outdated than that. The article is from August 2024 but it cites "a recent survey by Databricks" that from what I can tell isn't linked to, so who knows what data they're referring to.
I was deep into the big data ecosystem in the 2010s. Those numbers feel like they're from 2017 or so. Scala has been on a slide every since.
It's interesting that Odersky started with Modula-2 (implementing a Z80 compiler), did a PhD with Wirth, but there discovered that functional programming offered a level of theoretical rigor and mathematical elegance he missed in Wirth's imperative languages. Wirth was generally critical of the complexity and abstraction often associated with functional languages. Rather than rejecting Wirth's pragmatism, he carried it forward by attempting to make functional programming "industry-ready".
I can relate to Odersky, similar to him, while I appreciate Niklaus Wirth's work, I don't appreciate the quest to minimalism that he went down after Oberon.
For me the right path is Oberon => Oberon-2 and Component Pascal => Zonnon and Active Oberon.
Yes, I know he wasn't directly evolved with those ones.
I see the several revisions of Oberon-07 as an entertaining exercise in minimalism, which fails to understand the industry.
Something that Niklaus Wirth complained about in his rant about Software Engineering, not understanding why Java and C++ and not Oberon won the hearts of companies.
I was fortunate to attend his Oberon session on Oberon Day at CERN, 20 years ago, while a genius programming language designer, expecting software engineers to recognise great design and naturally embracing it, was expecting too much.
Minimalism is indeed the correct term (usually framed as simplicity) when looking at both, language and documentation. But at least it helped that there was always a working compiler and system, not a mere theory.
> I see the several revisions of Oberon-07 as an entertaining exercise in minimalism, which fails to understand the industry.
His main motivation was to minimize the amount of work porting his original system to his own, FPGA based processor board. His fans interpreted the “new” language more as a new prophetic proclamation, but in reality it was only about the feasibility of his post-retirement hobby project. This became clear at the latest when people wanted to run a benchmark on the system and discovered that the compiler couldn’t generate such large binaries. There was simply a fixed maximum size, but for many years no one noticed this.
He has always positioned his languages for education and limited himself to the systems that can be realized with them. If his goal had been to meet the needs of industry, he would have acted differently. After a very brief foray to an industrial job in the sixties, he immediately returned to academia and hardly looked back.
One could argue that Modula-2 was an attempt to fix Pascal for the industry, after all the dialects that sprung out of it, which he wasn't keen on, with the influence from Mesa, after his sabbatical at Xerox.
Also that the way it failed to be embraced by the industry, too busy with UNIX, C and C++, also had an effect on his point of view going forward.
> One could argue that Modula-2 was an attempt to fix Pascal for the industry
There is no evidence that Wirth e.g. ever directly or specifically rebutted Kernighan's famous paper, nor that Modula-2 was a response to it. Modula-2 was a child of the ivory tower (PARC), not industry. Wirth was rather an "escapist" who built his own worlds rather than fixing the real one. He saw Parnas' concepts "in action" during his sabbatical at Xerox. He didn't create Modula-2 to help industry; he created it because he wanted to replicate the Alto workstation experience (which became the Lilith) for his own use and for his students at ETH. Wirth was a brilliant "synthesizer" of academic ideas (Parnas, Hoare, Mesa) who built beautiful, self-contained gardens for himself and his students. He was never the "industrial repairman" that later apologists tried to paint him as.
Why should he?
That paper was only relevant among UNIX people, and largely ignored by anyone doing 8 and 16 bit home computing with Pascal and Modula-2.
It is no accident that to this day, it is the UNIX accolades that keep bringing it back every couple of months, most of whom never used a single Pascal compiler in their lifes, or aware that Modula-2 was already around.
Modula-2 relevance as systems language is quite easy to find out in some of his essays, and the companies selling compilers for Acorn, Amiga and PC.
You said that "One could argue that Modula-2 was an attempt to fix Pascal for the industry". By 1981, the C/Unix team was no longer a "rogue research group" in a closet; they were the architects of the dominant industrial paradigm shift (with Apollo Computer, Sun Microsystems, Silicon Graphics, and even Microsoft all using Unix and C). That's why I mentioned it. Wirth didn't care because his concern wasn't industry. Pascal users helped themselves: e.g. Lisa Pascal essentially included all features from C Kernighan (who refered to Wirth's original Pascal, not the derivatives) was missing and even a module and separate compilation concept (four years before Turbo Pascal); they could have used Modula-2, which was around at the time. While Modula-2 was hypothetically a "systems language", it lacked the pragmatic "dirty" features that C, Lisa Pascal, and Turbo Pascal embraced to actually build operating systems and drivers on commodity hardware (unless, again, they were added as an extension by the compiler vendors). E.g. Topspeed Modula supported inline assembly, Acorn Modula included extensions to call software interrupts directly with register mapping; almost all commercial vendors added extensions to bypass strict typing, or direct pointer increment/decrement to support C-style array traversal.
It is irritating that apparently C is fine having endless compiler extensions without which ISO C is equally unusable to implement an operating system[0], a sign of greatness, while the same argument is used to point out as design flaws when it isn't C we are talking about.
[0] - Unless helped by an external assembler, just like on the UNIX rewrite, when K&R C was initially created.
It is, of course, well known – or at the very least frequently and enthusiastically repeated – that a suitably drunk Odersky devised Scala whilst watching a Reese’s Peanut Butter Cup ad[0].
[0] http://www.nerdware.org/doc/abriefhistory.html
Martin Odersky did a fantastic job with Scala then, and also with Scala 3 IMO from a language design perspective. When I first got into Scala, I was blown away by the language features and the type system. It was the reason I got back into the JVM and the reason for getting into functional programming (not pure FP).
Scala is a great language, and functional programming (not pure functional) made me a much better programmer. And functional error handling is a fantastic way to model success and failure, whether you’re using Either or the newer Result type.
I have to both agree and disagree with some of the commenters here regarding why scala declined in usage. There are several reasons.
1. People just got fed up with the push toward pure FP and the complexity. Pure FP and category theory, and effect libraries are just not for the average audience.
2. Android support for Kotlin drastically reduced the momentum as well
3. Spark usage was pretty heavy driver for using Scala and I’m not sure about it’s used as much.
4. Scala became more and more niche as a result of item 1 above.
This being said, I switched to Kotlin for all server side work. I think a language and in particular the ecosystem, needs the vision/stewardship that can offer more practicality and balance in the language design, programming style, tooling, and frameworks. Kotlin just became a simpler language with better support for all of the above.
I can’t think of a better company to drive the development than Jetbrains. I don’t agree with all the choices, but Kotlin overall is a beautiful, simpler language, with all the practicality, and support needed to keep it going.
However, now that Java is making strides in the language features, as compared to historical improvements at the VM level, I’m curious to see how the market share for Kotlin outside of android is going to be affected.
Personally, I still prefer Kotlin for the practical FP support, Ktor as an HTTP server, and pretty good compatibility with Java. And lastly, I think there is enormous potential in multiplatform, as a strong alternative to typescript/react native for mobile.
Disclosure: I am biased as I’m developing some libraries and soon to be made (more) public server framework.
> However, now that Java is making strides in the language features, as compared to historical improvements at the VM level, I’m curious to see how the market share for Kotlin outside of android is going to be affected.
My employer has decided to abandon Scala, and they proposed Java as the language to head toward. I don't think Java's strides are fast enough to provide modern table stakes. In 2025, the big ones to me are:
1. null handling at the cultural and language level
2. abstractions over concurrency
For null handling, Java has Option, but you're just going to have to deal with the fact that basically any API or caller can give you null. This is not good enough in 2025.
For concurrency, Java has an excellent java.util.concurrent package (and the JVM is very good at concurrency in general). However, I've come to believe that it's a losing proposition to expect the average programmer to use concurrency primitives correctly, even at that level of abstraction. Every Java PR I review I have to add 20-30 comments about thread interruption, memory barriers, etc.
Structured Concurrency helps, but is new/in preview, and hardly helps with actually providing safer concurrency operations.
I think Java is doing the right things and the glacial pace of innovation at the language level is correct for protecting their users (contrast this with Scala 3...), but on the flipside I just think that it is hard to recommend Java vs C#/Kotlin.
1. There was never a push. Functional ecosystems are simply the ones that survived. You can't blame communities that keep the language alive for doing what they want, and not what you want. Without Typelevel and ZIO where would be Scala 3's adoption today?
2. Android has never been even remotely relevant to the space where Scala exists. And no, this was not a missed opportunity for the language. People who think Scala had a shot are completely delusional.
3. I'm personally convinced Spark was the worst thing that happened to the ecosystem as it brought a lot of attention, and indeed, drove adoption, only to result in an incredible amount of shitty code plagued by the worst annoyances in the JVM and big data space. Spark is the biggest open source project in Scala, yet Databricks doesn't seem to give a damn about the language and couldn't even be bothered shipping a Scala 2.13 runtime for years after its release. I sincerely hope Spark moves away from the JVM entirely.
Kotlin is really not any simpler especially with the constant feature creep that results in copying Scala features, only halfbaked. It's even less principled which is the biggest gripe against Scala having too many ways to do the same thing. There's nothing beautiful or practical about a language where people regularly write expression oriented code next to early returns.
Given that Scala-Android efforts predate Kotlin, Scala could have had a shot at Android if EPFL resources were allocated to it, like to Scala.js.
Kotlin is not simple at all, it has a lot of keywords for strange and very specific features and corner cases, it's hard to remember them all. Moreover, the Intellij Kotlin plugin is somehow slower than Scala's despite being a 1st party language and not having implicits, how they managed to achieve that is a mystery.
- The resources simply didn't exist, Typesafe couldn't even become profitable doing what Scala does best.
- Scala was a bad fit, especially on low-end and slow Android devices.
- Google doesn't like languages like Scala. They use it for Chisel but it's not a language allowed for backend services, while Kotlin is.
Any language pushed by Android overload has a shot at Android.
Kotlin would be irrelevant on the JVM space otherwise, only something being pushed by Jet Brains that some folks play with outside the company.
There would not exist a Kotlin Foundation which is basically Jet Brains in bed with Google.
I keep waiting for the announcement of Google's acquisition from Jet Brains.
Right and if you know the first thing about Scala, Kotlin, Google and JetBrains, it should be clear Scala on Android was simply never going to happen, even if Typesafe somehow managed to find extra millions in funding and could allocate dozens of people behind it.
It certainly would, had Google decided that would happen, and support the ongoing existing efforts from the community.
If you know anything about Google politics, you would know Kotlin only took off because of a couple of folks on the Android Tools team doing free advocacy for JetBrains.
In an alternative reality, if those same persons had been Scala heads, Jetpack Compose would be a Scala DSL today.
Scala was a bad fit for the Android runtime and the SDK. On a $200 Android phone with 2015 specs the performance aspect was definitely not a trivial argument against Scala; Kotlin has perfect interop with very little overhead, no conversions between collections (often slow and immutable in Scala), a nullability story that doesn't box everything in Option, ...
And most Googlers do not like clever languages with bad tooling, especially the ones working to productize languages and toolchains for Blaze and other internal tools.
All irrelevant when politics are involved.
You will never get me to say anything positive about the Kotlin advocates on Android team.
It isn't only Scala, it is using Java 7 samples to sell Kotlin, the original language for Android, still used for the large majority of Android tooling, where your argument fails flat.
They have begrudgingly being updating Java support, up to Java 17, when Java 25 is the latest LTS, because that great Kotlin interop with Java is useless when Android loses access to the Java ecosystem that keeps moving forward regardless of Android.
Some of them even don't have any ideas how out of date their Kotlin "improvements" over Java are out of date.
I'm not defending JetBrains or Google's decisions. But I don't see why anyone should try to rewrite history.
Scala had a decade head start. Many people at Google are aware of Scala, some being former LAMP students or staff. Google doesn't simply add a language to their small list of sanctioned toolchains.
Kotlin was specifically designed to win the politics argument, using technical merits: full interop, gradual adoption, low overhead, ability to target outdated Java bytecode efficiently (Kotlin used to inline lambdas for Java 6 bytecode for instance, while Scala boxed everything before invokedynamic). It doesn't matter whether one approach is objectively right or wrong, Kotlin fitted the bill and Scala did not. More importantly, Kotlin fitted the bill on Google's server side too!
Then of course JetBrains was tasked to replace the IDE with Android Studio, they could put dozens people backing Kotlin as a first-class Android language, until Google adopted it officially.
But even if Typesafe had somehow stumbled upon $100M in funding to do the same thing, it doesn't change the fact that Scala never had a chance.
Kotlin won Android on internal Google politics, zero technical merit.
Feel free to write another long reply on how Kotlin is somehow special, going to replace Java, while the first iteration of Kotlin Native was a failure with a broken design on its reference counting memory approach, and there is still no KVM to replace the JVM in sight, despite such greatness as pointed out in Android circles.
I haven't defended Kotlin's approach in any way, I don't know why you want to put words in my mouth.
However if you don't see why Kotlin was well positioned, while Scala was not, then you clearly don't know much about either language.
Technical merit is subjective, but different design decisions can precisely be made to win politics or not, and JetBrains made the right ones, first to convince people internally (who knew about Scala, you know), then Google, as they were fairly well aligned.
> People just got fed up with the push toward pure FP and the complexity. Pure FP and category theory
Amen. My eyes start to glaze over whenever I read about covariance.
It's one thing if a feature works because of category theory, but if you just "feel like arrays should be covariant", and then the actual category theorists come along and can't work with its limitations, maybe give it a miss.
Wanted to get into enterprise-level back-end development in 2025 and was really drawn to Scala, but ultimately learning C# or Kotlin seemed way more practical.
I love scala case classes and pattern matching. Too bad the compiler sucked (too slow) and it had some rather large footguns like implicits
If you haven't checked Scala 3, give it a try. Its syntax is now Python-like (indentation based), although you can also use C style if you prefer.
And it's faster (or maybe my laptop is faster).
Have error messages improved? I remember trying it few years back but the error messages made it hard to debug. Is it due to use of JVM? Sorry for my lack of knowledge since I rarely program in JVM based languages.
Compiler error messages improved significantly with Scala 3. IIRC there was a dedicated effort with Scala 3 to improve error messages and make them more actionable. Scala 2 error messages improved somewhat over time, but can still be obtuse.
Do you mean compiler errors or some other kind of error message?
Compiler errors got a lot better during the Scala 2.12 era.
Yes. It might have been errors when using Apache Spark with Apache Zeppelin notebooks. However, I must admit it was long time ago (2015-2016 era).
Disk partitioning labels: GPT, MBR, SUN, or BSD.
Answer: some PL prof used to do a lot of java back in his day
Scala is a great language. It's a little bit disappointing that Kotlin is the JVM language that's gained so much traction instead.
They really obliterated their momentum with how they went about Scala 3, unfortunately.
It was before this: It was never a huge community, but from very early on it was split thanks to some rather unfriendly, competitive personalities and very different goals. You didn't just use scala: you either ran scala with a Twitter stack, or a typesafe(now lightbend) stack, or a scalaz stack, or a cats stack, or a zip stack. And a lot of the people developing each stack didn't like each other. I've gotten to work with core contributors of multiple of those, and knowing that I wasn't a devotee of any stack led to hearing way to much complaining in pairing sessions about how The Others (TM) were slowing down the adoption of the language.
A language that is really popular can manage having 5 ways to do things, but a small community is just going to lose steam. And the fact is, all the ways work just fine in a vacuum, but you can't just get really mature tooling when everything is just so split.
Yeah, I think with a community as small as Scala's, you can't really afford:
a. fragmentation of the ecosystem b. repeated shuttering/abandonment of some of the most popular options (Lift, Play, Akka) c. splitting the language in two
The perception within and without my own employer (which heavily invests in Scala) swapped from "acceptable" to "this ecosystem is a dead-end and we need to get out" with the launch of Scala 3. It's possible they would have reached the same conclusion, but I don't think breaking every industry engineer's development tools for years is a good strategy.
I don't think it is a problem with Scala 3 itself. Scala 3 brought a lot of improvements, one of them is using semantic versioning. People used to complain a log about binary compatibility between versions in 2.x. Now it's here. I think that the slow adoption of Scala 3 is mainly due to one of its most successful projects: Apache Spark. To this day, Spark only supports Scala 2.13 although Scala 3 has been around for years now. This is both disappointing and frustrating because a lot of people were introduced to Scala thanks to Apache Spark.
The language is actually really nice. The "we won't ship dotty as the next version of Scala, just kidding, here it is", the breakage of editors and IDEs that lasted for years, etc (aka, the WAY they did it) make migrating a poor value prop. If I have to suffer worse tools and pay the tax of fixing them/updating them, then for each system when I think it's time to migrate to Scala 3 I might think it's time to migrate off Scala entirely.
It's possible that nothing could have reversed their existing trend, but I think it's fair to say that smaller communities (as another poster mentioned) can't afford this level of friction. Have we not seen Perl->Raku? Python2-3?
Additionally, while almost all of Scala 3 is an improvement over 2, whitespace significance seems like an awful hill to die on. Most people who value that sort of syntax in domains where Scala has made any inroads are already on Python, and we're going to alienate many existing developers in the (vain) hope of increasing marketability?
I learned scala due to load testing with Gatling.
I’ve always hated Java but Scala was super fun.
What really obliterated Scala’s momentum was PySpark overtaking Scala Spark coming from Python’s foothold in Data Science, columnar data warehouses carving out a big chunk of the batch processing pie as well, and then the Akka licensing change.
The Enterprise ecosystem quickly withered away, and now only type level programming diehards remain.
I think realistically we're looking at a lot of causes (which is not surprising; it's rarely a singular thing). Scala 3's momentum may have already been negative but how Scala 3 landed represented a nail in the coffin for a lot of individuals, teams, and organizations.
Scala 3 really landed at a bad time as the hype behind Spark, Akka, Play had already weaned off. Typesafe was struggling financially, and didn't back Scala 3 then (that went to VirtusLab).
Typelevel and ZIO really put a lot of effort to release many libraries on day 1 despite the hurdles with the 3.0 release, because these communities are alive and healthy. Yet Odersky is on a small crusade against monadic effect systems, which discouraged a lot of good people. On top of that there are neverending feuds and US politics...
Akka's demise started before the license change. It's an incredible piece of software but as it turns out, not so many people need stateful cluster sharding. Modern cloud architecture and simpler streaming libraries have made the Akka toolkit irrelevant to many use cases.
You're right about Spark and the next logical step will be removing the JVM from the equation entirely, which is already ongoing (see Photon or Comet).
Why is that? I think they did a lot of things right. Offer automatic conversions, backwards and forwards compatibility from a sufficiently recent 12.x version.
I think mostly Kotlin being simpler and Java gaining features ate the lunch. Also, software like Akka and Spark becoming less prevalent hurt because they were big reasons for devs to learn the language. Not to mention the community drama.
The only bad thing was that it took quite long for Scala3 to become available leading to a lot of stagnation.
From my perspective the two biggest challenges of the Scala 3 migration were macros and poor tooling support.
Macros were an experimental Scala 2 feature, but were used all over the Scala ecosystem. Because they were considered experimental a good migration story for them was never developed. That lack of support stopped migration efforts dead in their tracks at our company for a long while. It just wasn't worth contributing simultaneous support for Scala 3 and Scala 2 macros to every third party dependency who used Scala 2 macros. That said, we did it for some and lived on a fork for others.
IDE support for Scala 3 was really rough when it first released. We checked in on it with every IntelliJ release for roughly 3 years before we decided it was far enough along. Prior to that it was rough enough that we froze migration efforts in order to keep the tooling usable enough for engineers to be productive.
> IDE support for Scala 3 was really rough when it first released. We checked in on it with every IntelliJ release for roughly 3 years before we decided it was far enough along. Prior to that it was rough enough that we froze migration efforts in order to keep the tooling usable enough for engineers to be productive.
Same story for us - about 3 years before Intellij was usable, even then not up to what it had been on Scala 2. We still only have 2 Scala 3 repos, out of about 30, for my team, and we're actually MORE adventurous than most other teams at the company!
Well, IJ experience for Scala 3 is still noticeably worse than for Scala 2. We're still cross-compiling our work projects, waiting until Scala 3 support in Intellij is good enough to switch.
As other posters mentioned, a lot of it is about lacking critical mass in the first place. Making such a dramatic change is a high-risk thing, and Scala didn't have enough of a lead at all to justify it.
> The only bad thing was that it took quite long for Scala3 to become available leading to a lot of stagnation.
Unfortunately this isn't the only bad thing. The language overall is definitely a nicer language (though I complain about the whitespace change elsewhere). The tooling was broken for years, which actually stalled our team's migration. How could I advocate for moving to Scala 3, just to send everybody's editors and IDEs back to the stone age?
I'm not arguing that they built bad technology, I'm arguing that they ignored the reality: the value prop of moving to Scala 3 vs... moving to something else, at that point, isn't that compelling.
I remember being a big fan of Scala, and before Scala 3 it was looking to me that Kotlin was becoming a big competitor. Could that be, or do I have my timeline wrong?
It competes in some ways and not in others. It does a pretty good job of providing similar benefits as many Scala ecosystems, but providing approachability over purity.
Kotlin becoming The Official Android Language helps it quite a bit, though the future gets interesting if Google successfully abandons the JVM entirely to rid themselves of Oracle. I'm skeptical that Kotlin targeting multiple runtimes is a winning proposition, but it certainly seems to be doing a better job than Scala Native (also Rust is probably the better choice than Scala Native for that kind of code anyway).
I was first a big fan of Scala, and while I still like it, I am now really into Kotlin.
I don't find it disappointing: I tend to consider that Scala was an inspiration for Kotlin. Maybe Kotlin won by being simpler, and definitely because of the tooling and community: being backed by JetBrains and Google helps.
For a long time, the tooling was very limited with Scala, which must have slowed its adoption, right?
Kotlin is pretty nice. I think the build tool in Scala being so esoteric didn't help with adoption; I remember avoiding Scala for a few years because dealing with sbt left a horrible taste in my mouth.
Scala CLI should have happened 5 years before, but honestly sbt has improved a lot, the DX is mostly fine since the 1.0 release and it's maintained plugin compatibility for 8+ years.
Gradle is worse on several dimensions, which didn't really hurt Kotlin's adoption, nor seems to fundamentally bother Android developers (ok, they have little choice here).
I've used both fairly extensively. Scala is just "too much". Kotlin is perhaps not enough, but that's better than too much.
Except when you chain many collection operations... then it breaks horribly.
Can you elaborate on what you're referring to? I can see performance becoming a problem if you repeatedly chain non-optimisable (in bytecode) as excluding the in place operations I believe all ops re-allocate the collection.
Just use `.iterator` before chaining and the final collection will only be allocated once.
Ignore that person they don’t know what they’re talking about lol
[dead]