What is the purpose of Scala language?

Question

It is my opinion that every language was created for a specific purpose. What was Scala created for and what problems does it best solve?

Answer 1

One of the things mentioned in talks by Martin Odersky on Scala is it being a language which scales well to tackle various problems. He wasn't talking about scaling in the sense of performance but in the sense that the language itself can seem to be expanded via libraries. So that:

val lock = new ReentrantReadWriteLock
lock withReadLock {
   //do stuff
}

Looks like there is some special syntactic sugar for dealing with j.u.c locks. But this is not the case, it's just using the scala language in such a way as it appears to be. The code is more readable, isn't it?

In particular the various parsing rules of the scala language make it very easy to create libraries which look like a domain-specific language (or DSL). Look at scala-test for example:

describe("MyCoolClass") { 
  it("should do cool stuff") {
     val c = new MyCoolClass
     c.prop should be ("cool")
  }
}

(There are lots more examples of this - I found out this one yesterday). There is much talk about which new features are going in the Java language in JDK7 (project coin). Many of these features are special syntactic sugar to deal with some specific issue. Scala has been designed with some simple rules that mean new keywords for every little annoyance are not needed.

Answer 2

One more of the original design goals was of course to create a language which runs on the Java Virtual Machine and is fully interoperable with Java classes. This has (at least) two advantages:

• you can take advantage of the ubiquity, stability, features and reputation of the JVM. (think management extensions, JIT compilation, advanced Garbage Collection etc)
• you can still use all your favourite Java libraries, both 3rd party and your own. If this wasn't the case, it would be a significant obstacle to using Scala commercially in many cases (mine for example).

Answer 3

Since it's functional and uses actors (as I understand it, please comment if I've got this wrong) it makes it very easy to scale nearly anything up to any number of CPUs.

That said, I see Scala as kind of a test bed for new language features. Throw in the kitchen sink and see what happens.

My personal opinion is that for any apps involving a team of more than 3 people you are more productive with a language with Very Simple and Restrictive Syntax just because the entire job becomes more how you interact with others as opposed to just coding to make the computer do something.

The more people you add, the more time you are going to spend explaining what ?: means or the difference between | and || as applied to two booleans (In Java, you'll find very few people know).

Answer 4

Another goal of Scala was to bridge the gap between functional and object-oriented languages. It contains many constructs inspired (i.e. copied from!) functional languages. I'm thing of the incredibly powerful pattern-matching, the actor-based concurrency framework and (of course) first- and higher-order functions.

Of course, your question said that there was a specific purpose and I've just given 3 separate reasons; you'll probably have to ask Martin Odersky!