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.

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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
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3answers
912 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
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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 ...
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1answer
59 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 ...
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1answer
67 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 ...
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1answer
376 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
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1answer
285 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 ...
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0answers
134 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
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1answer
113 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
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2answers
191 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
184 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
240 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
555 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
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1answer
426 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
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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
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4answers
515 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
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2answers
91 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
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2answers
651 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
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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
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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
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1answer
61 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
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1answer
202 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 ...
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3answers
3k 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
997 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
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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
645 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
675 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
113 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
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6answers
468 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
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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
795 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
173 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
434 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 ...
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votes
3answers
620 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
912 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
351 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
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1answer
865 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
306 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 ...
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votes
2answers
224 views

Am I barking up the wrong tree with Scala? [closed]

Having some spare time, I've decided to learn a new programming language while developing - for fun, will never see the light of day - an insurance administration web application (insurance is the ...
6
votes
2answers
875 views

Node.JS or Scala for mobile and web apps

I am coming from a php background with some python as well. I want to start working on a different language for both web and mobile development. I am also interested in real time apps dealing with ...
2
votes
3answers
181 views

How to name nested function?

When you have a function that wraps another one in Scala. What do you call the nested function? I found this : def factorial(i: Int): Int = { def fact(i: Int, accumulator: Int): Int = { if ...
2
votes
3answers
572 views

Does macros support make Scala a Lisp dialect?

I've read recently that macro support in Scala is now official. I checked the documentation page and they are reminiscent to the LISP ones. In one of his essays Paul Graham writes that when "you add ...
2
votes
4answers
263 views

How to promote Scala to the management?

As a developer I like Scala and could tell the management about technical benefits of the language. But even if management understands that a superior technology has business impact, I fear that they ...
2
votes
2answers
702 views

Should I use semicolons to delimit Scala statements?

I'm used to delimit statements by a semicolon from Java, so naturally I do it in Scala code too. I also feel that the code is easier to read, because it's evident where one statement ends and another ...
7
votes
1answer
690 views

Why is the Scala Option type not called Maybe, just as in Haskell?

Why is the Scala Option type not called Maybe, just as in Haskell? Maybe makes a lot more "semantic sense" to me, but maybe Option has different behaviour I am not aware of. Is there any particular ...