Intro to Scala

High-level Overview

• Scala is a high-level, general-purpose programming language with support for both object-oriented and functional programming
• Scala is statically typed and compiled into Java bytecode (JVM instructions)
• All types and functions are objects (instances)
• It provides seamless Java interoperability — all classed from the java.lang the package is imported by default
• Designed for concurrent, distributed, and message-driven applications –  strong static systems, data science, and machine learning
• It has nested functions support
• Runs on JVM as well as JavaScript (Scala.js)
• SBT is a popular open-source build tool for Scala projects
• IntelliJ is a good Scala IDE
• Official Scala Lang –> tutorials

Scala vs. Java – Key Differences

	Scala	Java
Concurrency	Actor model	Thread-based model
Variables	Immutable by default	Mutable by default
Operator Overloading	Yes	No
Lazy Evaluation	Yes	No
Pattern Matching & Big Math	Yes	No
Build Process	Slow	Faster

Scala Syntax

object HelloWorld {
  def main(args: Array[String]): Unit = {
    println("Hello, world!")
  }
}

• Singleton Object model – a class with a single instance
• Unit is used to define a function that does not return anything, similar to void in Java

Variables & Types

// Declaring immutable variables 
// val <Name>: <Type> = <Literal>

val a: Int = 5
val b: Long = 100000000L
val c: Short = 1
val d: Double = 2.50
val e: Float = 2.50f
val f: String = "allaboutscala Donut Store"
val g: Byte = 0xa
val h: Char = 'D'
val i: Unit = ()

// Declare a variable with no initialization
var j: String = _

// Declaring mutable variables
// var <Name> : <Type> = <Literal>

var x: Int = 1
var y: String = "text"
var z: Double = _

String Interpolation

val x: String = "some text"
println(s"my variable text is $favoriteDonut")

Scala Frameworks

Big Data	Apache Spark – leading open sourced platform for large scale data processing
High Throughput Messaging	Kafka – high throughput distributed messaging system
Highly Concurrent Systems	Akka – build highly concurrent and distributed systems Finagle – highly concurrent servers with protocol agnostic APIs Spray – high throughput HTTP server
Other Frameworks	Play – scalable web applications Shapeless – added functionality to data types ScalaTest – testing framework Scalaz – additional semantics for functional programming Slick – rich data access layer

Scala Tutorials

GETTING STARTED

A SCALA TUTORIAL FOR JAVA PROGRAMMERS

ONLINE RESOURCES