Scala

An Introduction

Summary

• What is Scala?
• Why Scala?
• Installation and Setup
• Basics

What is Scala?

• First developed by Prof. Martin Odersky at École Polytechnique Fédérale de Lausanne (EPFL) in 2004
• Today adopted by many noteworthy enterprises:
  • Twitter, Netflix, Bloomberg, CreditSuisse, ING Bank, Databricks, Confluent, Mesosphere, LinkedIn, FourSquare, Lightbend, SoundCloud, Spotify, Nest, Sungevity, Workday, Pinterest, Tumblr, Airbnb, Apple, Sony, Cisco, eBay, The New York Times, The Guardian, BBC, Huffington Post, etc.
• Most of the Scala library is maintained by Lightbend (formerly Typesafe) based in SF
• Popularized by Twitter's switch from Ruby to Scala for many of its distributed services

At a Glance

Why Scala?

• Systems language
• Strongly-typed
• Very expressive
  • first-class functions
  • combinators
  • closures
  • case classes

• Concise and literal syntax
• Open source 
• Java interoperability
• Platform agnostic
• Rich collections library
• Blazing fast concurrency
• Emphasis on immutability

class Point(object):
    
    def __init__(self, _x, _y):
        self._x = _x; self._y = _y
        
    @property
    def x(self):
        return self._x

    @x.setter
    def x(self, value):
        self._x = value
        
    @property
    def y(self):
        return self._y
        
    @y.setter
    def y(self, value):
        self._y = value

point.py

public class Point {

    private int x;
    private int y;

    public Point(int x, int y) {
        this.x = x;
        this.y = y;
    }

    public int getX() { return x; }

    public int getY() { return y; }

    public void setX(int x) { this.x = x; }

    public void setY(int y) { this.y = y; }

}

Point.java

case class Point(var x: Int, var y: Int)

Point.scala

Concurrency

https://github.com/natemurthy/misc/tree/master/pools

https://github.com/natemurthy/misc/tree/master/threads

• Scala adds some neat abstractions
  around Java's concurrency primitives
  • Futures & Promises
  • Actors

• Some cool open source projects with signficant portions written in Scala
  • Play! Web Framework
  • Scalatra
  • Finagle, Finatra, Scalding (Twitter)
  • Akka / Spray
  • Breeze
  • Apache Spark
  • Apache Kafka
  • Apache Flink
  • Marathon

• A few apps Grid Systems has written in Scala
  • dgms-platform
  • realtime-aggregator
  • spark-ingestion-application
  • websocket-rabbitmq-bridge
  • rabbitmq-cassandra-bridge
  • nest-bridge
  • steffes-bridge
  • sep2-bridge

Installation and Setup

• Download Simple Build Tool (SBT)
  • http://www.scala-sbt.org/download.html
     
• Clone seed project
  • https://source.scit.solarcity.com/projects/GSLIB/repos/sbt-seed/browse

Basics

https://twitter.github.io/scala_school/