I'm not anti functional or Scala, but I'm yet to see any reports etc that actually indicate there is a pay off.
I have not seen Bay Area companies where previous Scala experience counts for more than inviting me to an interview. In my current team I know multiple developers who'd like to have more Scala and Java developers who don't know Scala or even Kotlin.
The underlying issue is that it's a complex language with many experimental and interacting features, which can and do cause a lot of distraction. This is not the fault of functional programming. Have a go at OCaml or F#, which are nice practical sweet spots.
Scala isn't simply an evolution of Java. It offers a type system that goes beyond what you can do in F# or OCaml. The fact it's multi-paradigm and plays nice with Java's OO model doesn't make it less functional than these two.
It affects the language very much, awkward currying and tupling, needing to wrap methods in objects. Subtyping also has many complex consequences. There is limited type inference and tail call optimisation versus functional-first languages.
> Scala isn't simply an evolution of Java. It offers a type system that goes beyond what you can do in F# or OCaml.
It offers higher-kinded types, but F# has units of measure, OCaml has polymorphic variants. Each has advanced features not offered by the other.
> The fact it's multi-paradigm and plays nice with Java's OO model doesn't make it less functional than these two.
It was not designed as a functional programming language first and foremost, that is my point.
I get that it is probably more intellectually stimulating for many engineers than the project they are working on, but it also reflects in over engineering of distributed systems for simple problems. I do wonder if there is really any net gains for a company to go the functional route.
I would love to see some research on this as people have been championing it for decades now, and seems suspiciously absent!
Then how do you explain that a very significant number of "top" tech companies have teams who manage to deliver products written in Scala or other FP languages?
Lots of tech companies have proved that you don't need to follow Google and constrain your workforce to a small list of vetted languages. Most teams who chose Haskell, OCaml, Scala, Rust... are productive and able to deliver products.
My question is simple as that, yet as engineers we get lost in the detail of the doing and some hand wavy suggestion that it makes things better, yet where is the actual evidence for this?
Be pro FP or not, or any other programming paradigm, lets say logic based (prolog etc), where is there any measures on how it benefits outcome.
I appreciate this isn't something that can be easily measured, but that is arguably a key problem with the state of the industry, that its emotion, intuition and bandwagon driven.
That is my personal experience, a tiny data point, again where are the studies that give some actual useful guidance?
I wrote a great project using Racket, everyone should use Racket, its cool, lets blog it ... gains momentum, its new its exciting it promises change ... people start to have different experiance, bad decisions are made ... new bandwagon, lets all rush to that yay. Having been around for long enough to see this cycle, I think it's right to ask for some well thought evidence, or gathering of trade offs to help decision making.
This feels to me like a low effort and vague criticism.
Essentially, this is a complaint about an arbitrary group of developers that they're playing around with tech (whatever that tech might be) instead of delivering...
Obviously, in this case you can't say that specific thing about Python/JS/PHP/whatever developers, because "monads and type theory" just don't apply in these languages. (I know Python has MyPy, but let's put that aside for the simplicity of the argument.)
But for some non-scala/functional engineers, somebody could complain that they're wasting time playing with GUI frameworks, testing frameworks, async libraries, whatever...
The truth is, people can clown around with any technology, just as people can deliver with Scala/FP or something else.
That is a lot less true since Scala 3.
> Subtyping also has many complex consequences.
Sure. But it also means I can use any library from the Java ecosystem, and that's a huge reason behind the big number of Scala jobs compared to other FP languages.
> There is limited type inference and tail call optimisation versus functional-first languages.
Limited type inference is typically what I (and my team) want, for the sake of self-documentation. Scala's type inference is plenty enough, and the few corner cases that were annoying in Scala 2 should be fixed in Scala 3.
Tail-call optimization is done the compiler. The lack of tail-call elimination is bothering the few maintainers of functional libraries that need to implement CPS and trampolines, but not really something the average developer will have to worry about. And it should come to the JVM with Loom, eventually.
> F# has units of measure
Scala offers more generic ways to do the same thing. Would F# need such a feature at the language-level if it had typeclasses?
> OCaml has polymorphic variants
I believe most people don't want structural typing in their GADTs.
> It was not designed as a functional programming language first and foremost, that is my point.
I don't think Martin Odersky would agree. It's not an either/or situation. Scala was designed to be a full-fledged functional language, and OO hybrid, compatible with (and leveraging) the Java OO model, and offering a strong type system that goes beyond what you find in most FP languages.
Personally, even though I haven't really thought it through deeply, I feel like Scala would be better if everything were curried.
> Subtyping also has many complex consequences
But also substantial benefits!
> There is limited type inference
I wish Scala would improve in this regard. Maybe paradoxically, inference works better with code tuned for subtyping and variance.
> tail call optimisation
This will be fundamentally solved by Project Loom. At least on the JVM (there's also Scala on JS and on LLVM).
> F# has units of measure
I dearly miss those. Type Providers even more so.
> OCaml has polymorphic variants
Could be nice in Scala. Or maybe not, can't tell now. And there's always the risk of too many features, which makes a language worse, not better.
> It was not designed as a functional programming language first and foremost
This is misleading at best. It was designed to show that the distinction between OOP and FP is arbitrary, not fundamental. In other words, Scala erases the distinction, it's fully OOP and fully FP. Scala has higher order functions, ADTs, pattern matching, a module system, like SML/OCaml. But it uses keywords `class` and calls it's instances "object" like Java. And it's interoperable with Java. But theoretically there's no fundamental distinction.
More languages are becoming more and more like Scala, btw.
https://www.lihaoyi.com/post/FromFirstPrinciplesWhyScala.htm...
And the concept of a programming language paradigm is fake from the start anyway ;)
https://www.cambridgeblog.org/2017/05/what-if-anything-is-a-...
Possibly misleading yes, it is certainly a subjective point. I guess it reflects the struggle I had doing FP in Scala versus alternatives. I don't think I'm alone either, the Haskell community contains a lot of Scala refugees. Note that I have not looked at Scala 3.
I think Scala is the language most actual functional programming on this planet takes place these days. Be it just FP or pure FP.
I especially like pure FP in Scala. One can do that with Cats Effect (from the TypeLevel family of languages) or ZIO. They're both awesome, so check them out and pick what you'll like best.
https://typelevel.org/cats-effect/
You don't even need to reach out to Scala 3 (still not as mature in its tooling support), you can have a great time with the latest Scala 2 (2.13).
> versus alternatives
I think of Scala as a opinionated take on ML and a module system that is tailored to JVM (and is seamlessly interoperable with Java) that just happens to have syntax heavy on braces/parentheses. Otherwise, what's not to like? :)
That's not quite precise, IMHO.
F# is an awesome language that I hold very dear, but it is a castrated form of OCaml. It has only a few features that OCaml doesn't have. For example Type Providers or Unit of Measurement. These are nice and useful features, they're not gimmicks, but they're not fundamental.
On the other hand, Scala isn't a hollowed out Haskell. Haskell, admittedly, is a more powerful language and has features Scala doesn't, like a linear type system. And it's just different, non-strict, whereas Scala is strict. But Scala is also very powerful in other fundamental areas, where Haskell is weak. Scala has a superior module system, it's biggest strength IMO. Haskell's modularity story is that great AFAIK.
It' technically true that Scala's fundamental building block is object, not function.
But that is in my eyes more of an implementation detail. Scala is a language that blurs the distinction between FP and OOP to the point of meaninglessness. You can do FP and still organize your code into classes/objects/traits (aka modules). You can choose to do side effects. Or you can waive them and do pure FP (like in Haskell) with TypeLevel or ZIO.
> it's an evolution of Java
I would say that it's kanda the other way around. Scala is a beacon that almost all languages are converging towards, not just Java.
https://www.lihaoyi.com/post/FromFirstPrinciplesWhyScala.htm...
> complex language with many experimental and interacting features
It doesn't have that many features. Some people even call Scala simple for this reason. But the features that is has are _very_ powerful. Some maybe even too powerful for my taste (implicit conversions anyone?). And they're orthogonal so they can be composed together.
Sadly, such composition can be brittle and non-beginner friendly, especially when it fails -- things like weird type errors or weird unexpected behavior at runtime, or compiletime for that matter, etc. So Scala will give you a lot of rope to hang yourself onto, if you'll be blindly taking it.
But it doesn't have to be that way. You (or a senior developer) have to know what you're doing. Then you can reap significant benefits.
It's good news that Scala 3 significantly improves on this front -- it emphasizes programmer's intent instead of Scala's internal mechanics.
Sure, in some languages, this risk isn't even on the table (Go, etc). But having power also comes with benefits, not only the potential problems I've described above.