Scala is a general purpose programming language principally targeting the Java Virtual Machine. Designed to express common programming patterns in a concise, elegant, and type-safe way, it fuses both imperative and functional programming styles.

learn more… | top users | synonyms

1
vote
2answers
121 views

If there's no problem treating a statement as an expression, why was there a distinction in the first place in some programming languages? [duplicate]

Why do we have the distinction between statements and expressions in most programming languages? For example, in Java, assuming f and g return ints, this still won't compile because it's a statement ...
4
votes
1answer
53 views

Coping with build order requirements in automated builds

I have three Scala packages being built as separate sbt projects in separate repos with a dependency graph like this: M---->D ^ ^ | | +--+--+ ^ | S S is a service. ...
2
votes
1answer
47 views

Is it good practice to use NoStackTrace in scala?

I came across the NoStackTrace mixin for Exceptions in scala. Is it good practice to use it, or should it be considered "internal" to scala and left alone?
2
votes
2answers
146 views

Java: method takes varargs of unrelated types

I have a Java factory method with a varargs array of Objects at the end. The array can contain any combination of Strings and ScaledJpegs. The theory being that an HTML table cell can contain any ...
1
vote
5answers
91 views

Many Arguments in Case Classes [closed]

I have generally read that having many (>4) arguments to a function/constructor is a bad practice. Is this still considered a bad practice? And is there a non-obvious reason? In something like a ...
3
votes
1answer
50 views

When to declare @throws with a Scala annotation - abstract parent or concrete implementation?

In this StackOverflow question I asked about the behavior of the @throws annotation in Scala. Now that I understand how it works I want to ask about best practices with using it. Here's a repost of my ...
0
votes
2answers
80 views

SOAP message testing

I am working in Scala/Java. I'm testing the messaging infrastructure of a part of my system that I did several years ago with CXF and Java. More specifically, I'm re-writing the specification of the ...
2
votes
0answers
46 views

Implementing a generic and covariant Set in Scala [migrated]

I'm struggling with manually implementing a simple purely functional Set that's also generic and covariant on its type parameter: Set must be a trait, allowing for multiple implementations. it must ...
8
votes
3answers
928 views

Is duplicate syntax for defining named functions a bad language design decision?

I am modelling a programming language for fun, and the syntax is heavily influenced by Scala - specifically function definitions. I have encountered a design problem because my language does not ...
5
votes
5answers
1k views

What negative consequences can arise from this language design rule?

Clarification: the rule is meant to prevent accessing variables that are not declared yet. Clarification 2: the rule mandates that the compiler follows calls to functions which are defined in the ...
3
votes
1answer
62 views

Why is subclassing TraversableOnce not recommended

Reading http://www.scala-lang.org/api/2.11.1/index.html#scala.collection.TraversableOnce: Directly subclassing TraversableOnce is not recommended - instead, consider declaring an Iterator with a ...
-1
votes
1answer
71 views

What is the session about simplicity that Martin Odersky suggested during the “Scala with style” talk? [closed]

The video of Scala with style is here: http://parleys.com/play/51c1994ae4b0d38b54f4621b/chapter21/about It's around 41:10 that he suggested another talk. I can not hear the name of speaker or the ...
0
votes
1answer
402 views

Why the Scala fascination with flatmap? (This doesn't seem to be the same for mapcat in the Clojure world) [closed]

In the Scala community - there is an apparent fascination with the FlatMap function. Now I understand that FlatMap is significant because it is used for the bind part of a Monad. (and that the ...
1
vote
1answer
288 views

Should we push for more JavaScript on the JVM, alongside Java and Scala? Or, if not, why?

With JavaScript becoming one of the most widely used languages around, I began asking myself why people do not find ways to use it extensively on the JVM. As a programmer who spends half day writing ...
1
vote
0answers
143 views

Why does my C++ (OpenMP) matrix operations code start incurring more cache misses running in parallel compared to Scala? [closed]

I have written code using C++ (OpenMP for parallelizing loops) which does lots of matrix operations. A single instance of the code runs very fast and completes in 0.2 seconds. For the same processing, ...
0
votes
1answer
119 views

Type Safety of Spray.io

Yesterday I read a tweet disparaging Jersey with JAX-RS due to run-time errors. Spray.io was mentioned in the tweet: Not even 5 minutes using Jersey / JAX-RS and already a runtime error due to a ...
2
votes
2answers
199 views

How do Traits in Scala avoid the “diamond error”?

(Note: I used 'error' instead of 'problem' in the title for obvious reasons.. ;) ). I did some basic reading on Traits in Scala. They're similar to Interfaces in Java or C#, but they do allow for ...
5
votes
3answers
190 views

Decreasing vars in Scala programs

I have been studying scala for the past week or so and the ideologies associated with it and functional programming in general. As expected, the leap from imperative to functional programming is not ...
1
vote
4answers
253 views

Alternatives to null values and option-like types

Related to this question i want to know if there is a concise way to eleminate null values out of code in general or if there is not. E.g. imagine a class that represents a user with birthday as ...
67
votes
1answer
7k views

What's the difference between Scala and Red Hat's Ceylon language? [closed]

Red Hat's Ceylon language has some interesting improvements over Java: The overall vision: learn from Java's mistakes, keep the good, ditch the bad The focus on readability and ease of learning/use ...
2
votes
1answer
565 views

Can Objective C categories serve the same purpose as Traits do in Scala?

The statement of the question seems little abstract to me, so please read the details below. Since the time when C++ was the first choice Object Oriented Language for almost anything, we had a big ...
7
votes
1answer
541 views

Pattern matching in Clojure vs Scala

What are the key differences between pattern matching in these two languages? I am not referring to syntax, but capability, implementation details, range of use cases and necessity. Scala ...
8
votes
5answers
3k views

Is there a clear leader amongst JVM-based languages? [closed]

What is the current status of these projects, and has any one (or two) emerged as a clear leader? To demonstrate my motives for asking this question, cast your mind back several years. Prototype and ...
5
votes
4answers
541 views

Do resumable exceptions make any sense?

Following up my previous question I wonder if resumable exceptions make any sense. It looks like nobody uses them in Java. Don't they use resumable exceptions because of Java limitations or just ...
0
votes
2answers
94 views

Parameterless & Empty-Paren methods in Scala

I'm learning Scala at the moment via Odersky's Programming Scala (2nd). I'm upto chapter 10 where he starts introducing parameterless and empty-paren methods. I just can't get my head around it. So ...
6
votes
2answers
692 views

What is the difference between self-types and trait inheritance in Scala?

When Googled, many responses for this topic come up. However, I don't feel like any of them do a good job of illustrating the difference between these two features. So I'd like to try one more time, ...
13
votes
4answers
2k views

Does functional programming add complexity in code? [closed]

For the entire past year I've been written Scala code (coming from a Java background). I really liked how you could create simpler and cleaner code, with vals, case classes, map/filter/lambda ...
10
votes
4answers
6k views

How Scala Developers Are Being Interviewed [closed]

How are Scala programmers being interviewed? What are the aspects that the interviewer looks for when interviewing a Scala developer?
19
votes
2answers
3k views

Is Clojure, Scala and other restrained by the JVM vs CLR [closed]

The Java implementors seem slow to adopt language improvements, for example compare C# with full closures, expression trees, LINQ etc.. to Java, and even the push back of some stuff to Java 8 will ...
0
votes
1answer
63 views

Preferred Scala code style for several embedded brace sets

I was wondering the correct way to format a situation such as this, where I have a def, a foreach and an if clause all nested, requiring braces. Currently I find it hard to read, and there is no ...
4
votes
1answer
210 views

Passing a Scala function to a Java 8 method

The following Scala code works and can be passed to a Java method expecting a function. Is there a cleaner way to do this? Here's my first pass: val plusOne = new ...
6
votes
3answers
2k views

Why Big Data Needs To Be Functional?

I started working on a new project lately related to Big Data for my internship. My managers recommended to start learning functional programming (They highly recommended Scala). I had a humbled ...
16
votes
3answers
4k views

When is it NOT good to use actors in akka/erlang?

I've been working with akka for 7-8 months now daily. When I started, I would be working on applications and notice that actors would be used basically anywhere once inside the actor system for ...
2
votes
1answer
1k views

JSON Library - Jackson or Play Framework? [closed]

Working on a Java and Scala code-base, there's a debate about whether to use Java's Jackson JSON or the Play Framework's JSON Library. After reading the Play JSON Docs, as well as Chapter 9 (JSON) of ...
23
votes
6answers
3k views

How do you encode Algebraic Data Types in a C#- or Java-like language?

There are some problems which are easily solved by Algebraic Data Types, for example a List type can be very succinctly expressed as: data ConsList a = Empty | ConsCell a (ConsList a) consmap f ...
8
votes
4answers
662 views

Design in “mixed” languages: object oriented design or functional programming?

In the past few years, the languages I like to use are becoming more and more "functional". I now use languages that are a sort of "hybrid": C#, F#, Scala. I like to design my application using ...
3
votes
1answer
99 views

Understanding special Scala syntax

I can understand this: List("one word", "another word") unzip (_ span (_ != ' ')) But don't get what's happening here below in the span. span takes a predicate and I think the braces can be omitted ...
3
votes
2answers
757 views

Learning Scala, feeling discouraged [closed]

I'm coming from a Java background and trying to learn Scala. At the moment I'm feeling pretty overwhelmed, there seems to be so much more to learn with Scala, so many different ways of doing the same ...
0
votes
1answer
123 views

Scala class with constructor requiring parameter of the same Class type

I can't remember but recently in one of the APIs I saw something like this class A (member:A){}. Scala does support it and there is no problem creating such a class but how do we initiate it and what ...
2
votes
6answers
477 views

How do you move beyond code examples without a project?

I am currently learning Scala and I find a mental blog of how to proceed to a degree where I can use Scala daily beyond the normal examples. I just do not have a particular project in mind of what I ...
8
votes
3answers
3k views

Functional Programming approach for a simplified game using Scala and LWJGL

I, a Java imperative programmer, would like to understand how to generate a simple version of Space Invaders based on Functional Programming design principles (in particular Referential Transparency). ...
6
votes
4answers
824 views

Why does Scala use the '_' operator for package import instead of '*' as in Java?

In my opinion, one of the greatest things about Scala is its interoperability with Java and its similar syntax. One thing that I found strange is the use of the _ operator for package wilcard imports ...
1
vote
2answers
178 views

Is short-circuit evaluation a consequence of call-by-name?

If the boolean operators &&, || are implemented as infix methods, then isn't short-circuit evaluation just a consequence of being implemented using call-by-name semantics, since, for example, ...
6
votes
1answer
454 views

Why appending to a list in Scala should have O(n) time complexity?

I am learning Scala at the moment and I just read that the execution time of the append operation for a list (:+) grows linearly with the size of the list. Appending to a list seems like a pretty ...
-6
votes
3answers
628 views

Are Extension methods (C#) and categories (Objective-C) the same as traits? [closed]

According to: Something similar to Objective-C categories in other languages? Static extension methods in C# are basically the same thing as Objective-C categories, so I'm going to lump these two ...
10
votes
2answers
940 views

How is Nothing a subtype of every other type in Scala

I am taking Martin Odersky's coursera course on functional programming with scala, and for now I have learned two things that together don't make sense: Scala doesn't support multiple inheritance ...
2
votes
1answer
371 views

Is there a representation for mixins or traits on UML?

Is there a representation for modern programming constructs that are becoming common in modern OOP/hybrid languages like mixins/traits/categories/partial classes ?
12
votes
1answer
882 views

Scala as a language for Generic Programming

In the paper “An Extended Comparative Study of Language Support for Generic Programming” by Garcia et al. an interesting comparison of programming languages features for generic programming is given: ...
19
votes
8answers
8k views

Why was Scala not implemented with C or C++

Does anybody know why was Scala implemented in Java and .NET instead of C or C++? Most languages are implemented with Cor C++ [i.e Erlang, Python, PHP, Ruby, Perl]. What are the advantages for Scala ...
4
votes
1answer
311 views

What kind of problems is an Android beginner likely to encounter in using Scala?

I am a hobbyist programmer who makes and maintains one production system, largely coded in Python, which now has to be ported to Android. I don't know Java at all. However, SL4A in Android makes ...