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Scala has way more language features than Java, that's for sure. It does have powerful abstractions and it makes a lot of things more elegant. You could say the

by xjru 14y ago

Scala has way more language features than Java, that's for sure. It does have powerful abstractions and it makes a lot of things more elegant. You could say the same about C++ compared to C. But in both cases, sensible people can disagree on whether or not the additional power justifies the additional complexity and those insane compile times. And just to be a little more specific in what I mean by complexity: What I mean is, how much do you know about what a particular piece of code does when looking at it in isolation? How much additional context do you need to figure out what it does? How many possibilities are there? Powerful syntactical abstractions are a double edged sword.

happy_dino 14y ago
> Scala has way more language features than Java I wouldn't say that. I think the main difference is that Scala spent its language design budget on more useful things compared to Java. Have a look at C# if you want to see a language with tons of features. > What I mean is, how much do you know about what a particular piece of code does when looking at it in isolation? How much additional context do you need to figure out what it does? How many possibilities are there? From experience, that amount of code is considerably smaller than Java because I can be pretty sure that some piece of Scala code usually won't mutate stuff all over the place.
- xjru 14y ago
  Immutability is not a language feature in Scala as it's not enforced like it is in Haskell, so you don't have any guarantees about what a piece of code doesn't do. Granted, you can make a better guess than in Java where mutability is concerned. Scala's syntax is flexible enough to let you build DSLs. It makes use of operator overloading, optional braces after method calls, infix methods, etc. All features that Java doesn't have. Being able to build DSLs is a good thing, but the whole point of DSLs is to hide some of the semantics of the underlying language and let you think in terms of the domain the DSL was built for. So there is clearly a power/complexity/understandability trade-off.
nuriaion 14y ago
Java can also become very complex because of it's simplicity. Sometimes it can be hard to read java code just because there is much more of it.
- lutusp 14y ago
  > Java can also become very complex because of it's simplicity. Another way to say this is that Java is a lower-level language than many newer languages, consequently it's much more wordy. And it is certainly wordy, to the degree that it's difficult to follow one's own code. And I see you make a similar point.
- xjru 14y ago
  I don't deny that. What adds to complexity more than verbosity, though, is that Java's lack of abstraction facilities leads to the overuse of frameworks, including byte code manipulation and excessive reflection. At that point it can get really obscure. But you can write straighforward Java, and on average reading someone elses Java code is easier than reading typical C++ code for instance. I don't have experience with reading other people's Scala code but it seems similar to C++.
- yareally 14y ago
  One of the worse examples I have come across is using BigInteger. You end up with code like this: BigInteger four = new BigInteger("4"); BigInteger sum = four.add(new BigInteger("2")); // assuming you won't need 2 again so why store a in var I never wished for the ability to do operator overloading anymore than I do when I have to use BigInteger in java. It just makes math look so unnatural and hard to read. You end up with variables all over the place to do Math on numbers or have to create a bunch of them in the method arguments. Just an utter mess when compared to the similar class in C# that does it with operator overloading.
ratherbefuddled 14y ago
It might be surprising but Scala actually has significantly fewer language features than Java. It is also more regular, there are fewer special cases and surprises. What Scala has done however is to pick particularly powerful features that are allowed to intersect as much as possible giving a lot of flexibility. At the same time it has introduced and encouraged functional programming concepts which are new to many OO programmers with Java backgrounds. This can make it seem a little daunting but I found it no more difficult to learn than any other language and easier than some. The compile times are simply because the compiler is doing a lot more. It's always going to be slower than the Java compiler, though there are still optimisations that can happen. That's a trade off, the additional expressivity and safety of the type system is either worth it to you or not. In the case of Play, you're getting compile time checked routes and templates for example. In terms of reasoning, it is much easier to reason about idiomatic Scala code in isolation than it is Java. This is because you have much richer type information and can apply the substitution model without being worried about mutation and side affects. It is true however that the flexibility you are given can be misused and you aren't forced to stick to a functional style, so when someone goes off the reservation that can result in hard to comprehend code. Most of the FOSS projects I've seen in Scala avoid this but YMMV.
- xjru 14y ago
  I don't doubt that Scala does the things that both languages do in a cleaner, more regular way. But the kind of syntactical abstraction that Scala supports lets you replace semantics that you can't replace in Java, which creates uncertainty. Consider this: a = b In Java or C this can only mean one thing. The value of variable b is assigned to variable a. In Scala it could mean the same thing, or the = operator could be overloaded and b could be a method call. If you need to know which one it is, for instance because you're trying to understand someone elses code, then you have more work to do than in Java.
  - ratherbefuddled 14y ago
    Not a great example because actually you can't override simple assignment but that aside, I was disputing that Scala had more features. It doesn't. I've acknowledged that the features it does have are more powerful and could be abused. The fact that operators are methods and can be overridden simplifies things - you no longer need to know and remember operators. They are always methods on the type you are looking at. This is what I mean by more regular and fewer surprises, the footprint is smaller. So you can use this simpler, more powerful feature to create DSLs. They are compile checked and are "real Scala". The tools autoamtically help you. Of course, DSLs exist in Java but they often involve tools like JTB and JavaCC, extra compilation steps, no compiler assistance for users - I could go on. Which is more complex? Anyway, I agree you could abuse the more powerful language features to write hard to comprehend code. However if you take a look at Scala code in the wild, you will see that these concerns so far have been largely theoretical and of course you can also write incomprehensible junk in Java or any other language should you wish. I'd encourage people to try the Coursera Scala course which is running again soon, and see for yourself.

by xjru 14y ago

happy_dino 14y ago

> Scala has way more language features than Java I wouldn't say that. I think the main difference is that Scala spent its language design budget on more useful things compared to Java. Have a look at C# if you want to see a language with tons of features. > What I mean is, how much do you know about what a particular piece of code does when looking at it in isolation? How much additional context do you need to figure out what it does? How many possibilities are there? From experience, that amount of code is considerably smaller than Java because I can be pretty sure that some piece of Scala code usually won't mutate stuff all over the place.

xjru 14y ago
Immutability is not a language feature in Scala as it's not enforced like it is in Haskell, so you don't have any guarantees about what a piece of code doesn't do. Granted, you can make a better guess than in Java where mutability is concerned. Scala's syntax is flexible enough to let you build DSLs. It makes use of operator overloading, optional braces after method calls, infix methods, etc. All features that Java doesn't have. Being able to build DSLs is a good thing, but the whole point of DSLs is to hide some of the semantics of the underlying language and let you think in terms of the domain the DSL was built for. So there is clearly a power/complexity/understandability trade-off.

nuriaion 14y ago

Java can also become very complex because of it's simplicity. Sometimes it can be hard to read java code just because there is much more of it.

lutusp 14y ago
> Java can also become very complex because of it's simplicity. Another way to say this is that Java is a lower-level language than many newer languages, consequently it's much more wordy. And it is certainly wordy, to the degree that it's difficult to follow one's own code. And I see you make a similar point.
xjru 14y ago
I don't deny that. What adds to complexity more than verbosity, though, is that Java's lack of abstraction facilities leads to the overuse of frameworks, including byte code manipulation and excessive reflection. At that point it can get really obscure. But you can write straighforward Java, and on average reading someone elses Java code is easier than reading typical C++ code for instance. I don't have experience with reading other people's Scala code but it seems similar to C++.
yareally 14y ago
One of the worse examples I have come across is using BigInteger. You end up with code like this: BigInteger four = new BigInteger("4"); BigInteger sum = four.add(new BigInteger("2")); // assuming you won't need 2 again so why store a in var I never wished for the ability to do operator overloading anymore than I do when I have to use BigInteger in java. It just makes math look so unnatural and hard to read. You end up with variables all over the place to do Math on numbers or have to create a bunch of them in the method arguments. Just an utter mess when compared to the similar class in C# that does it with operator overloading.

ratherbefuddled 14y ago

It might be surprising but Scala actually has significantly fewer language features than Java. It is also more regular, there are fewer special cases and surprises. What Scala has done however is to pick particularly powerful features that are allowed to intersect as much as possible giving a lot of flexibility. At the same time it has introduced and encouraged functional programming concepts which are new to many OO programmers with Java backgrounds. This can make it seem a little daunting but I found it no more difficult to learn than any other language and easier than some. The compile times are simply because the compiler is doing a lot more. It's always going to be slower than the Java compiler, though there are still optimisations that can happen. That's a trade off, the additional expressivity and safety of the type system is either worth it to you or not. In the case of Play, you're getting compile time checked routes and templates for example. In terms of reasoning, it is much easier to reason about idiomatic Scala code in isolation than it is Java. This is because you have much richer type information and can apply the substitution model without being worried about mutation and side affects. It is true however that the flexibility you are given can be misused and you aren't forced to stick to a functional style, so when someone goes off the reservation that can result in hard to comprehend code. Most of the FOSS projects I've seen in Scala avoid this but YMMV.

xjru 14y ago
I don't doubt that Scala does the things that both languages do in a cleaner, more regular way. But the kind of syntactical abstraction that Scala supports lets you replace semantics that you can't replace in Java, which creates uncertainty. Consider this: a = b In Java or C this can only mean one thing. The value of variable b is assigned to variable a. In Scala it could mean the same thing, or the = operator could be overloaded and b could be a method call. If you need to know which one it is, for instance because you're trying to understand someone elses code, then you have more work to do than in Java.
- ratherbefuddled 14y ago
  Not a great example because actually you can't override simple assignment but that aside, I was disputing that Scala had more features. It doesn't. I've acknowledged that the features it does have are more powerful and could be abused. The fact that operators are methods and can be overridden simplifies things - you no longer need to know and remember operators. They are always methods on the type you are looking at. This is what I mean by more regular and fewer surprises, the footprint is smaller. So you can use this simpler, more powerful feature to create DSLs. They are compile checked and are "real Scala". The tools autoamtically help you. Of course, DSLs exist in Java but they often involve tools like JTB and JavaCC, extra compilation steps, no compiler assistance for users - I could go on. Which is more complex? Anyway, I agree you could abuse the more powerful language features to write hard to comprehend code. However if you take a look at Scala code in the wild, you will see that these concerns so far have been largely theoretical and of course you can also write incomprehensible junk in Java or any other language should you wish. I'd encourage people to try the Coursera Scala course which is running again soon, and see for yourself.