What Are The Benefits Of Scala?

UPDATED 2019

I can name some simple points in plain language from my limited experience:

  1. Properties. C++ and Java had this notion of a public getter/setter function "property" wrapped around an internal class variable which led to large amounts of boilerplate code. C# formalized this as a real language feature and reduced much of the boilerplate in C# 3.0 with auto-implemented properties. Scala classes define trivial properties simply as regular read only vals or read/write vars. The class may later choose to replace those with get or get/set methods without affecting client code. For this, Scala provides the most elegant solution with the least language features and complexity.

  2. Arrays use regular generics. In Java/C#, int[] is redundant and confusing vs List<int> or List<Int>. Worse, in Java, List<Int> has lots of runtime overhead, so many developers have to know to use int[]. Scala avoids that problem. Also, in Java/C#, arrays support (covariant) casting, which was a mistake, that they now can't fix because of legacy concerns.

  3. Scala has better support for immutability. val is a basic language feature.

  4. Scala lets if blocks, for-yield loops, and code in braces return a value. This is very elegant in many situations. A very small plus is that this eliminates the need for a separate ternary operator.

  5. Scala has singleton objects rather than C++/Java/C# class static. This is a cleaner solution.

  6. Pattern matching. Object unpacking. Very nice in a large numbers of situations.

  7. Native tuples.

  8. "case classes" which are what most other languages would call record types or named tuples.

  9. Fancier standard library with more elegant collections.

  10. Multi-line strings. String interpolation formatting.

  11. Optional semi-colons.

Cons.

  1. Java has caught up a lot. Java 8 was first released in 2014, but it took several years for older Java versions to be phased out and the new Java 8 features to be fully used across the Java ecosystem. Now, lambdas and closures and basic functional collections, with support for filter/map/fold are quite standard for the Java ecosystem. More recently, Java has added basic var local variable type inference and has multi-line strings and switch expressions in release builds preview mode.

  2. Scala is complicated. I'd highlight features like implicits to be inherently confusing.

  3. Scala has minimal backward compatibility. Scala 2.10 artifacts are incompatible with Scala 2.11.

  4. Building a Java API for other JVM-language developers like Scala or Clojure or Kotlin is normal, well supported and accepted. You generally don't want to build APIs in Scala that cater to non-Scala developers.


Also, take a look at this recent news item post on Scala's site: "Research: Programming Style and Productivity".

In his paper, Gilles Dubochet, describes how he investigated two aspects of programming style using eye movement tracking. He found that it is, on average, 30% faster to comprehend algorithms that use for-comprehensions and maps, as in Scala, rather than those with the iterative while-loops of Java.

And another key quote from the news item:

Alex McGuire, who writes mission critical projects in Scala for power trading companies, says of Scala "The conciseness means I can see more of a program on one screen. You can get a much better overview. When I have some mathematical model to write with Java I have to keep two models in my head, the mathematical model itself and the second a model of how to implement it in Java. With Scala one model, the mathematical one, will do. Much more productive.”

You an read the rest of the post and other linked items there.


Go read Daniel Spiewak's excellent blog series about Scala. With Scala you can keep:

  • all your Java libraries
  • all the advantages of running on a JVM (ubiquity, administrative tools, profiling, garbage collection etc)

But you can write Scala code:

  • more concise and clear than Java (especially using more functional style, such as in the collections library)
  • it has closures and functions as part of the language
  • it has operator overloading (from the perspective of usage)
  • it has mixins (i.e. interfaces which contain implementation)

Tags:

Java

Scala

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