![Hello Scala
object Greeting {
def main(args: Array[String]) {
println("Hello World !!!")
}
}
● Look maa no semicolon
● Object ?](https://image.slidesharecdn.com/scalaintro-130323074533-phpapp02/85/Introduction-To-Scala-5-320.jpg)
![Variables
object Greeter {
def main(args:Array[String]) {
val message = “Hello” // final equivalent
message = “Bye !!” // won't work
var num = 2
num = 3 // will work
}
}](https://image.slidesharecdn.com/scalaintro-130323074533-phpapp02/85/Introduction-To-Scala-6-320.jpg)
![Tuples are DTO's – Ted Neward
● Returning multiple values from a function
● def calculate() : Tuple2[Int, String] = (2, "Ted")
● val v = calculate // Scala convention no parenthesis
● Accessing each of the values
– v._1 : refers to the first return value
– v._2 : refers to the second value
● Scala has had a big impact from dynamic languages
like Ruby](https://image.slidesharecdn.com/scalaintro-130323074533-phpapp02/85/Introduction-To-Scala-9-320.jpg)
Introduction To Scala
- 1. scala> “Hello Scala” Scala stands for “scalable language.” The language is so named because it was designed to grow with the demands of its users.
- 2. History ● The design of Scala started in 2001 at the (EPFL) by Martin Odersky, Odersky had previously worked on Generic Java and javac, Sun's Java compiler ● Scala was released late 2003/early 2004 on the Java platform ● Recent Scala release 2.10.0 ● On 12 May 2011, Odersky and collaborators launched Typesafe Inc., a company to provide commercial support, training, and services for Scala
- 3. Scala Adopters ● Twitter ● FourSqaure ● LinkedIn ● Sony ● OPOWER ● Siemens
- 4. Features ● Scala is OO ● Scala is Functional ● Strongly Typed – even more so than Java ● Type Invariance ● Implicits – Analogous to Ruby's open classes ● Duck Typing – anything that quacks is a duck ● String Interpolation
- 5. Hello Scala object Greeting { def main(args: Array[String]) { println("Hello World !!!") } } ● Look maa no semicolon ● Object ?
- 6. Variables object Greeter { def main(args:Array[String]) { val message = “Hello” // final equivalent message = “Bye !!” // won't work var num = 2 num = 3 // will work } }
- 7. Classes ● class Person(val name:String, val id:Int) ● Is equivalent to Java's class Person { private String name; private Integer id; …. } ● val p = new Person(“John”, 1)
- 8. Functions def calculate(msg:String, count:Int) : String = msg.take(count) ● def implies a function declaration ● msg and count are parameters ● : String implies the return type of the function ● In Scala everything returns a value ● Even assignment x = 1 returns a special value called Unit (A feature coming from dynamic languages like Ruby)
- 9. Tuples are DTO's – Ted Neward ● Returning multiple values from a function ● def calculate() : Tuple2[Int, String] = (2, "Ted") ● val v = calculate // Scala convention no parenthesis ● Accessing each of the values – v._1 : refers to the first return value – v._2 : refers to the second value ● Scala has had a big impact from dynamic languages like Ruby
- 10. Collections ● List(1,2,3) // no need to pass the type info ● Set(1,2,2) ● Map(1-> ”One”, 2-> ”Two”, 3-> ”Three”) ● Ranges: 1 to 10 / 1 until 10 by 2 ● Array(1,2,3) ● Default collections types are immutable
- 11. Commonly used methods ● val l = List(1,2,3) ● l.head / l.tail ● l.foreach(println) ● l.map(_ * 2) ● l.filter(_ > 1) / l.filter(_ < 2) ● l.exists(_ < 0) ● l.reverse ● l.take / l.drop ● ….
- 12. Higher Order Functions ● Functions taking functions are called higher order functions ● Cannot pass functions in Java not until Lambdas in Java8 ● def foo(f : (String => Boolean)) : String = if (f("Ted")) "Cool" else "Not Cool !!" ● l.filter / l.foreach / l.map are all examples ● This is a standard feature of all Scala libraries
- 13. Case classes ● case class Person(name:String, id:Integer) ● val p = Person(“Martin”, 2) // no new needed ● It automatically adds getter's, equals and hashcode ● Case classes are used for pattern matching
- 14. Pattern Matching ● Switch with steroids :) List(1,2,3) match { case Nil => "Empty" case x if x.length == 3 => "Blaah ..." case _ => } ● Match also returns a value ● You can have conditional expressions as well ● It works for all data types
- 15. Excited? Any Questions? ● Resources – Scala lang – Programming in Scala 2nd Edition – Typesafe Inc. – IDE Support (Intellij & Eclipse Scala IDE) – Pune Scala User Group ● Follow me on twitter for live Scala feeds :)