edit: Ok, Hatred is a strong word. I shoud have used dislike instead.
Random annoyances off the top of my head - you can't necessarily understand an isolated function unless you know what implicits are being used, crazy overuse of operator overloading and slow compilation times (this has improved over the years).
You don't have to learn Scala, you could learn Clojure, F#, OCaml or Haskell. They would all teach you interesting aspects of programming and then you could come back and examine Scala with a broader perspective.
F# might not be the best place to go then:
http://stackoverflow.com/questions/2210854/can-you-define-yo...
implicit val option = new Traverse[Option] with MonadPlus[Option] {
def point[A](a: => A) = Some(a)
def bind[A, B](fa: Option[A])(f: A => Option[B]): Option[B] = fa flatMap f
override def map[A, B](fa: Option[A])(f: A => B): Option[B] = fa map f
def traverseImpl[F[_], A, B](fa: Option[A])(f: A => F[B])(implicit F: Applicative[F]) =
fa map (a => F.map(f(a))(Some(_): Option[B])) getOrElse F.point(None)
def empty[A]: Option[A] = None
def plus[A](a: Option[A], b: => Option[A]) = a orElse b
def foldR[A, B](fa: Option[A], z: B)(f: (A) => (=> B) => B): B = fa match {
case Some(a) => f(a)(z)
case None => z
}
}
Anyway, scala needs less weird operators, not more. Looking at you, parser combinator library.
I get the sense the Java community is also unused to interacting with other languages, because for a long time the JVM was a world unto itself. Most languages have a spectrum of "neighbour" languages and so users are used to working with at least slightly different alternatives. Scala is possibly Java's closest neighbour (Groovy is not really popular enough to show up on the radar of most Java devs) and it's become something very different, so there's a real culture shock just trying to talk to each other. A lot of Scala folks take a lot of assumptions for granted that are very alien to Java folks.
None of which really takes away from the language itself, if you're willing to learn on your own or tolerate a few insults when you ask for help. IMO it is very much worth it: Scala is genuinely the best practical language available today (it has more than its fair share of warts but they're mostly for JVM/Java compatibility, which makes it so much easier to introduce to business than e.g. Haskell).
For example gradle buildscripts are groovy, as is the spock test framework.
You can read the other unemployed developer's take on Groovy's development history at http://blackdragsview.blogspot.com/2015/04/about-being-paid-...
http://stackoverflow.com/research/developer-survey-2015#tech...
But you are completely right that there's also a lot of negative sentiment around it. Here are two possible reasons I can think of (I am sure there are others).
1. Scala does not form part of an established programming language tribe. It is neither a better Java nor a Haskell on the JVM. So people are challenged in their assumptions; they don't know what it is, and react negatively in order not to have to learn more.
2. Scala is pretty successful. So people in neighbouring language communities sometimes feel frustrated that a seemingly (to them) inferior language gets traction and their perfect language gets less. I saw some of that when Java eclipsed Smalltalk in the 90's. I never met a community as spiteful of Java as the Smalltalk one.
The thing that fascinates me is scala is like an art. It's like a new Obfuscated Perl Contest, but for functional programming. It doesn't really serve a purpose in legitimate business.
Scala code doesn't scale, it compiles too slow due to having too many features in the syntax. They took features normally meant for a standard library / external projects and literally augmented them into the syntax.
Scala, in it's current form, is a pipe dream. It really needs to be start over, but drastically simplified. Perhaps it should try to take a hit from Golang for compiler time advice: Simple languages compile fast and are easier to optimize.
The harder something was to succeed at, the harder you'll try to convince yourself it wasn't wasted effort.
1. The REPL is not very helpful: You cannot look up documentation a la IPython (i.e. myFunc?) or inspect objects easily to find out how things work
2. There always seem to be 10 ways to do the same thing. This makes it much harder to understand other people's code than when there is just one way to do it.
3. The type system seems less helpful than Haskell's (e.g. why is "asdf" + 3 not a type error?)
The antithesis is when we see posts about how "Go's too simple".
I'm not sure I've seen any "Python's too simple" posts. Maybe Go's criticism is based on some other factor?
"One could also argue that this provides evidence of simplicity" Or one could argue that it provides evidence of complexity, since you need to hold much more information in your head to achieve the same results.
3. Some of these are backwards compatibility. You can get a more helpful typesystem by setting a few flags: https://tpolecat.github.io/2014/04/11/scalac-flags.html
edit : typo
Apart from occasional issues in the community Scala is criticised for being too complex: https://www.youtube.com/watch?v=uiJycy6dFSQ
I think Paul Phillips agree with the overall direction of Scala and thinks it's the best programming language out there, but disagrees on design details and compiler inner workings.
Idiomatic Scala is not a grab bag of features or paradigms. It is firmly based on programming with expressions and using the type system to improve abstraction. Statements and mutable data structures show up when interfacing with external systems or for performance reasons. The Collections libraries are arguably "object-oriented" as that term is commonly understood, but this is not typical for application code. However, object-oriented features such as objects, classes, and traits are the basis of Scala's module capabilities.
For programmers coming from 20th century mainstream languages that are all based on programming with statements, mutable variables, and are arguably a thin abstraction over the machine itself, programming with Scala can be a challenge. If you want to do your familiar imperative style of programming, Scala is going to be painful. Use another language. But if you would benefit from a type system and good support for expressions, then Scala is possibly the best choice currently for growing business applications. We are not in 2005 any more.
Scala is not ideal as an introduction to functional programming. Other languages, such as F#, SML, OCaml, and Haskell have better, simpler syntactic support for features associated with functional programming.
People who dislike on Scala are probably either stuck in the past or don't have pain that Scala would solve.
Just like how people won't touch Python because of its whitespace, people won't touch Scala because of the JVM.
It can be -- and is -- for some people.
> Actually, being JVM-compatible is an attraction point.
Sure, for some people. People have different preferences.
What turns be off from looking into it much:
Verbosity. It seems that it can't infer types in as many places as an ML. I prefer rather succinct code. I understand Scala has a powerful type system and it isn't always possible, but... ugh.
OO. Scala seems to want to really embrace Java's OO model fully, and that's a bit ugly. It's probably a good practical decision but feels like a turn off. Again, I haven't used Scala, this is just an impression I have.
I think the problem is that Hindley-Milner type inference doesn't play with OO type hierarchies, and so Java interop (which is a key motivating purpose of Scala) means worse inference than ML-family langs for Scala. Its not really that its a powerful type system that is the issue (Haskell has a more powerful type system, but better inference.)
> OO. Scala seems to want to really embrace Java's OO model fully, and that's a bit ugly.
I think "embrace" is a bit strong, but it wants to support it fully, because its a key part of the interop story.
Scala is, by definition, a superset of Java. It's not ideal, but there aren't really any good alternatives.
I started learning Scala (it got me into functional programming) but dumped it for the same reasons as Java. It's bloated. I also question Scala's longevity.
I'm happily using Elixir and Clojure these days, but I mainly do web stuff so YMMV.
Elixir as a language may or may not last. I'm betting it will, but even if it doesn't, it works well with Erlang which is going nowhere.
There's more a case against Clojure, granted. I think because Scala is seen as a bridge language is the another reason why it won't last.
Also the compiler drama... http://www.infoq.com/news/2014/09/scala-compiler-forks
That said, nothing does exactly what Scala does. Fluently mixing imperative, lazy, OO and functional styles isn't really common. Neither is the wealth of concurrency constructs available to Scala programmers through the standard library and Akka.
I'm writing a compiler in (not for) Scala right now and it's pretty sweet.
This is not true.
My intent was to imply that since jython is a python implementation, the language itself is more widely 'accepted'. Where accepted may mean "in general use and considered to be a good langauge". Groovy has been called a better java by some. Another example would be JRuby.
One of my pet hates in C++ was implicit casting and I'm hearing that Scala does similar, which is putting me off it.
To my mind Scala is a very unmagic language; very complex libraries are written for it, but they're never magic, they're always ordinary Scala code and ordinary Scala features, just combined in clever ways. E.g. typeclasses are a language feature in Haskell, but in Scala they're just a pattern that you implement using implicit parameters. Actors and messages are a language feature in Erlang, but in Scala they're just a library with methods that you call. Type-level functions are a language feature in e.g. Idris, but in Scala (e.g. Shapeless) they're just a technique making use of implicit resolution.
Free learning resources. There are no good free scala books which can teach you the language in the way it is supposed to be learned. Not something expected of a language which wishes to compete with something like Java on the longer run. The biggest issue I have faced so far is learning from scattered blog post all over the internet explaining the powers of scala, even before introducing how to use the very basic features to build simple things.
There is too much assumption about what the programmer already knows, or about the programmer's background is; while introducing these features. As some one who is not familiar with the Math behind most of these functional programming concepts, every thing goes over like water poured over a stone when the documentation talks about Types, Category theory, Monads. In fact it took me a great deal of simplification, and thought to understand concepts like map, reduce, foldLeft, foldRight. Most of it was in language totally unpalatable to an ordinary programmer. Talking in a language understandable only to Phd students won't work for nearly all of the programming world.
So far my introduction to Scala has been similar to seven blind men describing an elephant by touch various parts of the elephant's body.
Partially free:
Atomic Scala also has at least a free sample, which expects basically no programming experience at all: http://www.atomicscala.com/free-sample/
Scala for the Impatient is also nice, but is more intended to help programmers get up to speed with Scala as fast as possible: http://www.horstmann.com/scala/index.html
That kind of says it all. Read different things from different places. No one single coherent documentation.
I have only dabbled in Scala myself, kicked the tyres as it were. My question was, is this an Ocaml or Haskell with good interop with the Java ecosystem? The answer is no but I don't hate Scala for it, I just moved on. But many folks would have persisted and tried to make it into something it's not and gotten miserable in the process.
When I used to work like that, I'd write code, and constantly be checking that it compiled. I'd be watching my test dashboard and feel happy turning the lights green. But it was definitely a crutch.
If you asked me to code without a compiler I'd make basic syntax errors. I'd let basic, predicable bugs slip through because they weren't covered by my tests. In my rush to turn the next light green, I wasn't thinking enough.
Maybe that's not how you work, but if it is, try building once a day and turning syntax highlighting off for a couple weeks. For me, (being forced to) work like that for a while has helped me long term.
It's split into two, the people who wish Scala is Haskell (shapeless, scalaz &c) and the people who want Scala to be Enterprise Quality™
It causes lots of issues, as their goals for the language are completely different and Scala devs are usually in one camp or another.
As an aside, I always think that if your problems are much better expressed in Haskell, why are these developers not using Haskell?
Generally because your boss won't let you.
Here's an example of a post censored from StackOverflow: http://stackoverflow.com/questions/3606591/why-does-intellij...
Here's a backup of the post that was mirrored: http://w3facility.org/question/why-does-intellij-idea-compil...
There is one word to describe the mind of a scala die-hard: Solipsism. The view or theory that the self is all that can be known to exist. [1]
[1] https://news.ycombinator.com/item?id=9389563
You see the way they squirm? They can't accept any criticism and therefore refuse improvement. They just want to sit there and be hobbyists. Not on my investors' dime!
Isn't it more likely that some comments are downvoted by the general HN population, because they don't add anything useful to the debate?
By the way, I just clicked your link, and I can't really how they support the point you are trying to make...
http://codahale.com/the-rest-of-the-story/
http://codahale.com/downloads/email-to-donald.txt
Having worked with Scala; I'd say I love it.
Having worked with Scala; I'd say don't use it for most projects.
It is not the best language to start learning FP. Wrap your head around a dedicated FP language and if you still feel the need for a hybrid FP/OO language Scala is definitely worth a look.
However as it is a hybrid I've felt it made my code just too complex. Compared to Java there are a dozen more ways in Scala to fix something; and often you struggle to find the best way. This takes a lot of learning and it just isn't worth it. It's a great and elegant language in many ways, but I've come to dislike a lot of features of it.
Simplicity is one of those things that make a beautiful codebase. See also (recently featured on HN);
http://kotaku.com/5975610/the-exceptional-beauty-of-doom-3s-...
Something I find different is that most C# developers like writing C#, they may dislike many other parts of the ecosystem, but they generally enjoy the language. However with Scala developers, I find that many of them seem to dislike the language.
To cast a broad stereotypical brush, it seems like there are 2 main groups of Scala developers. There's those who are really into FP, and would love to be getting paid to write Haskell all day, but unfortunately Scala is the only option they can convince their employer to adopt. So they begrudgingly choose it because it has some of what they want, but they are forever wishing it was better & making their frustrations known.
Then there's the other side, which are developers coming from Java (or other OO languages) after hearing about the benefits of FP/Scala. They're either not using Scala professionally, but want to learn, or are just starting to use it at work. They are much more enthusiastic about the language.
Unfortunately, the first group are often more vocal, and it puts off newcomers.
If you find yourself in the future "hating" all the programming languages, this isn't necessarily problematic, it might just mean you have a good understanding of programming languages. Just try to remain polite and remember that there's more than one way to see most scenarios.
* Dirty (opposite of Clean) language.
* Relationship between theory and practice is so far away from being "1 to 1".
* "Not In My Head" anti-patterns (something that will constantly require checking your notes/internet if you haven't worked with it within e.g. a month) everywhere.
Everything seems to be made overcomplicated on purpose for no reason (apart from JVM compatibility I guess, which is no excuse for me as user). Starting from simple things, variable function declarations, so many ways to declare functions, so much theory on var/val/def/lazy/ and how they differ at some corner cases. Function vs. Method stuff in combination with currying/partial application makes things so overcomplicated with so many corner cases which I will never be able to remember. I mean I have many pages of my notes from time I studied Scala, consisting just of corner cases and explanations of why they are present.
If you consider how Golang is viewed by many - as huge step back in our knowledge of language design. I consider Scala as step back in what is known in clean code, overall lessons from designing nice products. It just makes me feel like, it betrays everything I care internally and if Scala becomes dominant platform, it would just show to me that we as an industry just don't have standards and can accept just anything, we will never have something nice, close to perfect.
So my stance on Scala:
* If you just want to learn functional programming - pick something else, F# for me looked a lot cleaner and much closer to "1 to 1" - you can just apply functional theory without fighting the language.
* If you looking for language to make you happy - don't pick Scala. Unless you're into "The Abyss" thing @ Crockford.
* If this is for the money or because it sucks less than X (e.g. Java) in some ways - Scala is good consideration.
.. additionally, I always found the scala equivalent of the javadocs harder to read.
The end result (for me) was that I'd download, say an HTTP library, all the method names would be things like '/' and '?' - and you couldn't actually see what a minimally functioning code should look like due to all of the implicits flying around.
If you compare this to java, which was undoubtably more verbose, but was easier to take and unfamiliar library, squint a bit, and see how the building blocks roughly fit together, using a combination of reading the docs, and looking at the intellisense in your IDE.
It's a very powerful and expressive language. That translates to "completely unreadable by people without at least a few months direct experience in it." If you plan on introducing people with little to no scala experience to your code base regularly you will probably want a different language or to severely limit your allowed feature set.