scala

It has always been a dream of mine to write Eclipse plug-ins in other languages like JavaScript, Groovy or Scala.

The list-construction operators in Scala make the return conditions for both cases quite readable and easy to understand.

In the case of XPath, you are able to use certain parts of XPath syntax directly in Scala, as it just gets translated into a function call.

Recall that type information is often inferred in Scala (unlike Java), meaning we don't always show type annotations explicitly.

You should now be prepared to read a fair bit of Scala code, but there's plenty more about the language to put in your tool belt.

It still wanted half an hour of sunset as he left the door of the Scala palace.

Before we begin, I'll lay out a few functional concepts that are required to understand why Scala looks and acts the way it does.

If I am trying to develop some software that works on binary data, I don't want Scala to optimize for me behind the scenes.

Scala combined with Spring makes it quite easy to transparently inject services into all kind of objects instantiated at runtime.

Java programmers looking to call into Scala should also be familiar with traits as a mechanism for using Scala.

But enough of the abstract overview: programmers like to see code, so let's take a look at what Scala can do.

Both Fan and Scala are trying to take software scalability to the next level, but I think we are taking different paths to get there.

Using Scala just for the tests meant we got to use it in anger without impacting production code directly.

Remember that the compiler can pull all sorts of tricks, just as long as the final result obeys the semantic meaning of the Scala language.

Scala is an attempt to incorporate functional concepts and terseness without losing the richness of the object paradigm.

Note that the return value of a get on a Scala Map is not the actual value corresponding to the passed key.

In practice, I've never seen this happen with a trivial example so I guess we'll have to take the Scala designers' word for it.

Scala enables you to define a new construct that lies halfway between an interface and a class, called a trait.

The hotel is also close to the Stock Exchange, the La Scala Opera House; and is within walking distance of shopping malls and boutiques.

The stack is made up of Rails for the front side, C, Scala and Java for the middle business layer, and MySQL for storing data.

Tuples are not a game-changing feature, just another one of those "niceties" that makes Scala a powerful language to use.

When we were learning new Scala features, we chose whether to use them based on whether the intent of the resulting code was more obvious.

Scala's case classes and its built-in support for pattern matching model algebraic types used in many functional programming languages.

18th century magnificent opera house, built similarly to La Scala in Milan and San Carlos in Naples, is one of the prettiest in Europe.

We ended the last chapter with a few "teaser" examples of Scala code.

This expression is actually the body of an "anonymous function" , called a function literal in Scala.

You may have noticed that the compiler did not complain when the file was named upper3. scala and the object was named Upper.

The only drawback is that the methods do not actually exist in Scala code and cannot, thus, be called by other Scala code.

You can see from the above example that Scala allows classes to be declared inside one another, or "nested" .

If I asked you to describe Scala in a sentence, how would that sentence look like?

So I can only imagine how hypnotizing those songs and anthems can be live at the Scala del Calcio.

Since Scala enumerations are just regular objects, you could use any object with vals to indicate different "enumeration values" .

Have fun with that, and let me know if you find work programming in Scala!

InfoQ: So how do you think Scala will look like in 5 years in terms of the language and its surrounding ecosystem?

Martin Odersky: The company aims to provide the best products and support for commercial and community users of Scala.

Look carefully at what the scala interpreter said the first command returned, double (Int)Unit.

The only static feature the Scala language offers is (companion) objects, whose counterparts in Java are singletons.

The Scala compiler is easily able to infer this information, so there's no need to be redundant.

In Scala, the last expression in a function is the return value, although you can have return statements elsewhere, too.

The feature uses reflection, and works not only for Scala code but just as well with Java.

Unlike the Java platform, Scala does not require the semicolon to terminate a statement if the termination is obvious by the line ending.

It also has access to the multitudinous multitudes of existing Java libraries out there, making for a (potentially) easier migration path.

Scala is compelling because it feels like a dynamically typed scripting language, due to its succinct syntax and type inference.

Separate compile and run steps aren't required for simple programs that have few dependencies on libraries outside of what Scala provides.

In Scala, the list is like the array in that its core definition is a standard class from the Scala library, List[T].

Also, although this is a minor nit, Scala does not require the file containing a class definition to mirror the name of the class.

Even if they never factor into a new design, Scala code uses lists extensively throughout its libraries.

When looking at the callback pattern from a Scala perspective what we actually see is a cumbersome implementation of a 'function'.

Milan made no mistake on opening night at 'La Scala del Calcio' and presented their fans with a impressive victory and three stunning goals.

Scala has no void type, but there is an equivalent type called Unit.

A lot of it boils down to Scala's focus on its static type system versus Fan's focus on modularity and meta-programming.

I think Scala is a really great language and I'm always on the lookout of good stuff to steal from it.

Instead, Scala supports a singleton object construct to support those cases where exactly one instance of a type is needed.

Yet, Scala gives you all the benefits of static typing, a modern object model, functional programming, and an advanced type system.

Throughout this book, we will use the symbol scala-home to refer to the "root" directory of your Scala installation.

In the next four chapters, we'll explore Scala's approach to object-oriented programming, starting with traits.

Scala is a general purpose programming language designed to express common programming patterns in a concise, elegant, and type-safe way.

This is not the case in Scala, where we are able to pass in a method literal, or closure.

Also, Scala does not support "static" or class-level members of types, since they are not associated with an actual instance.

But considering the original Person also had no synchronization code around those mutable setters, the Scala version is safer to use.

Scala encourages you to use immutable values whenever possible.

Scala can usually infer the return type of the method (but not the types of the method arguments), so we drop the explicit declaration.

And, despite what others may say, don't fear just using Scala as a better Java-without-semicolons in the first few days, weeks or months.

In fact, its byte code can be hard to distinguish from byte code created through Java source code, and its performance is on par with Java.

However, for optimal performance, Scala uses the underlying primitives types of the runtime whenever possible.

Based on what you've learned so far, you can already start using Scala to reduce your programming workload.

By default the Scala compiler does not generate getters and setters that comply with the JavaBeans convention.

So with Scala, you get a much more expressive language than Java, but it runs on the JVM and runs as fast as Java.

A custom build of scala-library. jar works best, at least for now.

Scala uses a number of techniques to minimize unnecessary syntax, making Scala code as succinct as code in most dynamically typed languages.

The core codebase behind guardian. co. uk - the one on a two week release cycle - as of two weeks ago has one single Scala class within it.

Scala offers quite different capabilities, the integration of Object Oriented with the Functional programming style.

These results indicate that cells of this neural stem cell line migrate from the scala tympani to Rosenthal's canal and the organ of Corti.

To summarize, if you type scala on the command line without a file argument, the interpreter runs in interactive mode.

When I pass the code block created by passing my target number as a parameter, Scala curries up a new function.

Of course, the logical flip-side of packaging is import, Scala's mechanism for bringing names into the current lexical namespace.

Scala uses square brackets to denote generic type, instead of the angle brackets used in Java programming.

We learned how flexible Scala's syntax can be, and how it facilitates the creation of Domain-Specific Languages.

Chances are, the more the code reviewer sees the "functional" part of Scala, the more attractive this version is.

Scala aims at providing a programming language which unifies and generalizes key concepts from both object-oriented and functional styles.

I stumbled across Scala and instantly realized it was what I was looking for.

The Scala programming language has been catching the eye of a number of developers as of late.

This is what the Scala compiler does, so there is nothing too tricky about this.

Of the set of newer JVM languages, Scala is one of the few that is statically typed and it is the best known among them.

Scala also has some pretty-printer classes for printing XML with all of the right spacing, tabs, and formatting.

With Scala's pattern matching, your cases can include types, wild-cards, sequences, and even deep inspections of an object's variables.

In the next chapter, we explore how the fundamentals of object-oriented programming work in Scala.

A recent meeting report mentioned that the Scala IDE will get its own release schedule, what is the intention behind that?

There is no place like home as they say and back amongst the loyal supporters in 'La Scala del Calcio' they are unbeatable.

We could be forcing Scala's XML library to traverse the graph once for each element or sub-element desired, which could get slow over time.

As opposed to languages that only support single inheritance, Scala has a more general notion of class reuse.

Scala adopts the package concept that Java uses for namespaces, but Scala offers a more flexible syntax.

InfoQ: What was your reason for choosing Scala for a web framework?

There is also at least one disadvantage of Scala's constraints on constructors.

This model is based on message passing, and is somewhat similar to the actor model used in Erlang and Scala.

We feel that the extra effort required day to day to use Scala will promote more careful reflection about your designs.

He learned to speak competent Italian and became an opera buff, attending performances at La Scala in Milan.

From there, Scala splits into two major branches, where the "primitive types" inherit from scala.

Using named arguments, one can selectively change values for the copied instance, as shown on the Scala website.

As with other traditional functional languages, Scala requires that functions (in this case a method) must always return a value.

Before we dive into object-oriented programming, there's one more essential feature of Scala that you should get acquainted with: traits.

Part of the power of Scala is that it encourages developers to create immutable objects by default.

That makes it an immutable object (like a string in Java code), as is common in Scala.

SUnit: Part of the standard Scala distribution, in the scala. testing package.

Knowledge of Scala is not assumed, and instead this article tries to introduce some of Scala's syntax and idioms.

Scala's focus is clearly on a sophisticated type system which can catch as many errors as possible at compile time.

Scala is statically typed which allows it to provide generic classes, inner classes and even polymorphic methods.

By doing so, the usage of existing Java frameworks can be improved and simplified.

However, there is one tricky step: For our code to run, it also needs code from the standard Scala library.

Scala supports single inheritance, not multiple inheritance.

Recall from Chapter 1, Zero to Sixty: Introducing Scala that we highlighted the synergy between pattern matching and polymorphism.

There's so much talk about in Scala, but our time this month has elapsed.

You'll be up and running in a few minutes.

Scala takes a similar approach, but it has some advantages.

We'll emphasize how the concise syntax of Scala helps you work better and faster.

Regexes in Scala should contain no surprises if you've used them in other programming languages.

For instance, starting with the familiar call to System. out. println demonstrates Scala's fidelity to the underlying Java platform.

Scala uses objects for situations where other languages would use "class-level" members, like statics in Java.

Then we explored Scala's enhancements to looping constructs and conditional expressions.

I've also shown you how Scala revisits traditional object-oriented concepts, finds them wanting, and reinvents them for the 21st century.

Keep learning and embrace features of the language incrementally.

In fact, recently, a number of new languages like Scala, Clojure, and F# have evolved, all promising to simplify concurrency.

In fact, it was former Parma coach Nevio Scala who inspired me, not just me, but a lot of coaches who were inspired by Parma .

Also, keep in mind that the interoperability between Java and Scala is bidirectional.

Start the scala interpreter by typing scala and the return key on your command line.

Scala represents a new breed of language which obliterates these arbitrary restrictions.

But, as the static language, Scala-lover, my main goal is to talk less, and listen more to see how we can make the Ruby APIs better.

Barbara Vignudelli, a soprano at the famed La Scala opera house in Milan, has had no solid food for two weeks.

So, Scala traits preserve separation of concerns while giving us the ability to compose behavior on demand.

Lift also makes Comet-style Ajax perform especially well thanks to Scala's actor-based concurrency system.

Scala lets you define more than one argument list for a method.

The reason has to do with the way the interpreter converts statements in scripts to valid Scala code before compiling to byte code.

And while both approaches are certainly viable, that's not where the real "hotness" of Scala and concurrency comes from.

Even the most familiar language features are supercharged in Scala, let's have a look at the lowly if statement.

Next, notice the definition of main, which, as with Java code, is the accepted entry point for Scala programs.

In Lift, you use XHTML files that included some extended markup that allow for Scala to inject dynamic content.

In Scala, the enclosing class can't see a private member, but Scala provides another way to declare it visible to the enclosing class.

The app servers (affectionately called "flapps" ) are written in Scala, are stateless, and are horizontally scalable.

A season of the composer's opera "Alcina" (pictured above) has just begun at La Scala in Milan.

This demonstrates a level of access control available in Scala that does not exist in the Java language.

I won't tackle Scala Groovy integration in this article, although there is a lot of potential synergy between the two languages.

This provides a degree of flexibility in access specification far beyond what the Java language provides.

With Scala's native support for XML, you can use a template-style syntax to insert dynamic data into an XML structure.

Like most programming languages, Scala gives you multiple options for parsing XML.

Scala allows function names to include non-alphanumeric characters.

Replace the standard Scala library with the Android library talked about above.

All of the libraries we were using already published versions for multiple Scala versions so that all just worked.

Whenever we refer to executing a script, we mean running a Scala source file with the scala command.

Hence, at the byte code level, there is no connection between Scala enumerations and the enum constructs in Java and C#.

Scala is a language that addresses the major needs of the modern developer.

Scala is a language that addresses the major needs of the modern developer.

The only tricky part is Scala syntax, which is markedly different.

Then, you'll see what Scala does to rewrite that history for the greater benefit of us all.

We'll discuss overriding abstract and concrete members in detail in Chapter 6, Advanced Object-Oriented Programming In Scala.

For now, we'll wave farewell to Scitter and start the happy hunt for a new project to solve with Scala.

Scala lets you nest class declarations, like many object-oriented languages.

We'll explore the visibility rules in the section called "Visibility Rules" in Chapter 5, Basic Object-Oriented Programming in Scala.

So, you can define packages in files independent of their "physical" location.

Scala may also work with older versions of Java but there is not formal testing done for those situations.

Such people have usually relished the opportunity to work with Scala.

Such people have usually relished the opportunity to work with Scala.

The Scala compiler uses clever techniques to map Scala extensions to valid byte-code idioms.

In this month's guide to Scala, I revisit the history of multiple and private inheritance in the Java language.

Following the conventions of Java, the root package for Scala's library classes is named scala.

The Scala compiler is very modular and supports plug-ins so it was a lot easier to adapt.

Note that Scala uses square brackets [. . . ] for parameterized types, while Java uses angle brackets.

Even future JVM-based languages like Scala are considering modularity.

The documentation for the Scala tools and APIs are especially useful.

The real win, though, is that in Scala, the code can be written to assign the result to a val, instead of a var.

This chapter discusses uses of Scala that promote succinct, flexible code.

As a result, Scala generates both accessor (String firstName(void)) and mutator (void firstName_$eq(String)) methods.

The installed documentation also includes details on the scala tool chain (including sbaz) and code examples.

To run the program, you compiled it with scalac FriendFeed. scala and then scala FriendFeed, as in Listing 9.

We discuss these subtleties in the section called "Command Line Tools" in Chapter 14, Scala Tools, Libraries and IDE Support.

Scala implementing Java interfaces and subclassing Java classes is 100% seamless.

We'll see how in the section called "Overriding Abstract Types" in Chapter 6, Advanced Object-Oriented Programming In Scala.

So, to avoid ambiguities, Scala uses square brackets instead for parameterized types.

The first import statement imports all the types in the scala. actors package.

If I have to do bit manipulation of large amounts of binary data, why is it, that Scala's primitive types are immutable?

Along the same line, why does Scala only have object types?

Recall from Chapter 1 that Scala uses square brackets ([. . . ]) for generic type parameters.

Scala is distributed under a BSD license and has been deemed stable for several years.

In Scala, the primary constructor is the entire body of the class.

However, in Scala, any expression can be used as the default, as long as it can compile where used.

This means that Scala's version of protected is more restrictive (although arguably more intuitively so) than the Java version.

La Scala theater in the same year he sang for the first time the Arab-Israeli Duke of Mantua.

Scala provides a complete mixin solution, called traits.

Scala is functional: Scala is also a functional language in the sense that every function is a value.

This means that there is no strict need to port to Scala layer by layer.

A new Scala plugin JDK2IKVM was created that applies the source transform in a batch mode.

Next, we'll dive into more Scala syntax, emphasizing various keystroke-economical ways of getting lots of work done.

All of this leads us to the real powerhouse of the Scala control construct suite: the for construct.

An effective unit-testing library named ScalaTest is available for Scala (see Resources).

Here is a summary of the rules for when explicit type annotations are required in Scala.

Scala lets you choose the approach that best fits your design problems.

The easiest way to find out is to write a small set of JUnit tests in Java code rather than in Scala, so let's do that.

The infamous scala mobile, which maintained a rigid link between Italian wages and prices, was scrapped in 1992 after a long struggle.

You can also find downloads for the API documentation and the sources for Scala itself on the same downloads page.

Note that Scala, like C#, requires the override keyword whenever you override a concrete method.

There are several key features provided by Scala which demonstrate its object-oriented nature.

If you misspelled it, the Scala compiler would catch this and give you an error.

Scala is a statically typed language and runs as fast "native" Java.

The backslash is actually a method of the class scala. xml. Elem.

Formally, Scala calls numer and denom methods without parameters, which are used to create a quick-and-easy syntax for defining accessors.

By making maximum use of Scala's liberal syntax and rich methods, Specs test suites are readable even by non-developers.

Scala is attractive for situations where a single, all-in-one language is preferred.

We'll discuss abstract types in more detail in Chapter 5, Basic Object-Oriented Programming in Scala.

In this case, the object that stockPrice refers to can't be changed, because Doubles in Scala are immutable.

We'll explore this class in greater detail in Chapter 5, Basic Object-Oriented Programming in Scala.

What makes Scala a great environment to build a web framework in?

The Any class in Scala is primordial, similar to java. lang. Object.

Following Scala's convention, we use the term method for a function that is tied to an instance.

Lastly, and perhaps most important for my purposes, there is an excellent webapp framework for Scala called Lift.

The 2. 6 version has some subtle differences, though, so downloading and installing directly from the Scala Web site is recommended.

Along came Scala, which neatly unifies these two worlds.

We'll discuss these exceptions in Chapter 5, Basic Object-Oriented Programming in Scala.

You compile and run such programs in one shot with the scala command.

This is just more evidence for the theory that Scala learns from the historical pain points of Java development.

We'll discuss the difference between reference and value types in the section called "The Scala Type Hierarchy" .

The singleton pattern is baked directly into Scala and is used anywhere you would use static methods or variables in the Java language.

Typing the code in the scala interpreter will tell us what happens.

There are many reasons to be seduced by Scala.

This is described in more detail in a note from the main Scala site (see Resources).

NET version of Scala is also under development that generates CLR byte code.

Remember that object denotes a singleton in Scala.

The posterior arch of stapes was situated in the prozone of scala.

In Scala, all operators are functions on a class.

Until next time, remember, Scala puts the fun(ctional) back into programming!

Return statements are optional in Scala.

This Scala script converts strings to upper case.

InfoQ: What would you say to a manager why he should trust in Scala instead of using his favourite Java platform?

Scala's functional orientation is worth exploring, and not only because you've run out of objects to play with.

Notice that even though this is a method on a Scala object, it is taking a Java object (java. io. InputStream) as a parameter.

This is a common idiom in Scala to provide a simpler, more type-safe way of doing enumerations.

For all practical purposes, we can mix and match inheritance across both the Java language and Scala without too much concern.

The only thing different in our case is that we start with . scala files.

You can find a "how to use" guide here and a slide presentation overview of Scala. Net project here.

We will examine Scala's support for pattern matching in more detail in Chapter 8, Functional Programming in Scala.

If you compile these files with scala, you can run the client as follows.

We'll discuss Nothing in the section called "The Scala Type Hierarchy" in Chapter 7, The Scala Object System, but its name is suggestive!

Now let's see what Scala has to offer in the way of a better workaround.

Each year during the Rio Carnival there is the Scala Gay Ball which is a national televised event .

For more information on the Scala command-line tools and other resources, see Chapter 14, Scala Tools, Libraries and IDE Support.

sbaz is installed in the same bin directory as the scala and scalac command-line tools.

We'll discuss type erasure in more detail in Chapter 12, The Scala Type System.

Powerful, new, and innovative languages such as Scala, JRuby, and Groovy run on the JVM, giving you other dimensions in which to write code.

There is another alternative for earlier versions of Scala.

Scala does not have static methods, fields, or initializers.

Among other things, you can use Scala to produce the very same POJOs needed for other programming environments, such as Spring or Hibernate.

GPars implements the actor model using many of the concepts from Erlang and Scala.