1 $ scala
2 Welcome to Scala version 2.9.1 (OpenJDK 64-Bit Server VM, Java 1.7.0_51).
3 Type in expressions to have them evaluated.
4 Type :help for more information.
5 
6 scala> println("Hello Scala World!")
7 Hello Scala World!
8 
9 scala>

 1 scala> val x = 10
 2 x: Int = 10
 3 scala> x = 12
 4 <console>:8: error: reassignment to val
 5        x = 12
 6          ^
 7 
 8 scala> var y = 10
 9 y: Int = 10
10 scala> y = 12
11 y: Int = 12

1 scala> val lst = List(1,2,3,4,5,6,7,8,10)
2 lst: List[Int] = List(1, 2, 3, 4, 5, 6, 7, 8, 10)
3 
4 scala> val arr = Array(1,2,3,4,5,6,7,8,9,10)
5 arr: Array[Int] = Array(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)

1 scala> val radiation = Map('a' -> "alpha", 'o' -> "omega", 
2                            'g' -> "gamma")
3 scala> radiation('g')
4 res5: String = gamma

1 scala> val T = Set("casey", "drew", "jade")
2 scala> val V = Set("drew", "jade", "glen")
3 scala> val S = Set("alex", "hunter", "casey", "drew")
4 scala> val U = V union T union S union 
5                  Set("blair", "erin", "francis", "era")
6 scala> val commonSet = S & T & V
7 commonSet : scala.collection.immutable.Set[String] = Set(drew)

 1 scala> val tuple1 = Tuple1(1)
 2 tuple1: (Int,) = (1,)
 3 
 4 scala> val tuple2 = ('a', 1)
 5 tuple2: (Char, Int) = (a,1)
 6 
 7 scala> val tuple3 = ('a', 1, "name")
 8 tuple3: (Char, Int, java.lang.String) = (a,1,name)
 9 
10 scala> tuple1._1
11 res0: Int = 1
12 scala> tuple2._2
13 res1: Int = 1
14 scala> tuple3._1
15 res2: Char = a
16 scala> tuple3._3
17 res3: String = name

 1 scala> import java.util.Calendar
 2 import java.util.Calendar
 3 
 4 scala> val now = Calendar.getInstance()
 5 now: java.util.Calendar = java.util.GregorianCalendar[....]
 6 
 7 scala> val hour = now.get(Calendar.HOUR_OF_DAY)
 8 hour: Int = 19
 9 
10 scala> println( if(hour < 12) "good afternoon" else "good morning")
11 good morning

 1 scala> val numbers = (1 to 10) toList
 2 numbers: List[Int] = List(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
 3 
 4 scala> for(n <- numbers) print(n + " ")
 5 1 2 3 4 5 6 7 8 9 10
 6 
 7 scala> var index = 0
 8 index: Int = 0
 9 
10 scala> while(index < numbers.length) { 
11          print(numbers(index) + " "); index += 1
12        }
13 1 2 3 4 5 6 7 8 9 10
14 
15 scala> var index = 0
16 scala> do {
17          print(numbers(index) + " ")
18          index += 1
19        } while (index < numbers.length)
20 1 2 3 4 5 6 7 8 9 10

 1 scala> val dow = now.get(Calendar.DAY_OF_WEEK)
 2 dow: Int = 3
 3 
 4 scala> dow match {
 5         case 1 => "Sunday"
 6         case 2 => "Monday"
 7         case 3 => "Tuesday"
 8         case 4 => "Wednesday"
 9         case 5 => "Thursday"
10         case 6 => "Friday"
11         case 7 => "Saturday"
12       }
13 res20: java.lang.String = Tuesday
14 
15 scala> dow match {
16         case x if x == 1  || x == 7 => "Weekend"
17         case _ => "Workday"
18       }
19 res21: java.lang.String = Workday

 1 val text =
 2  """|Hello Scala World
 3     |Scala is a wonderful language
 4     |OO + FP make Scala wonderful
 5     |You should also try Scala""".stripMargin('|')
 6 
 7 val nextToScala = """.*\bScala (\w+).*""".r
 8 > nextToScala  : scala.util.matching.Regex = .*\bScala (\w+).*
 9 
10 for (line <- text.split("\n")) yield line match {
11   case nextToScala(w) => w
12   case _ => ""
13 }
14 > res0: Array[String] = Array(World, is, wonderful, "")

 1 scala> var divisor = 0
 2 divisor: Int = 0
 3 
 4 scala> def divide(n: Int) = 1 / divisor
 5 divide: (n: Int)Int
 6 
 7 scala> def divide(n: Int) = n / divisor
 8 divide: (n: Int)Int
 9 
10 scala> try { divide(10) } catch {
11          case e: ArithmeticException => "Check your calculations!" 
12        }
13 res34: Any = Check your calculations!
14 
15 scala> divisor = 2
16 divisor: Int = 2
17 
18 scala> try { divide(10) } catch {
19          case e: ArithmeticException => "Check your calculations!"
20        }
21 res35: Any = 5

1 scala> def f(x: Double) = x * x
2 f: (x: Double)Double
3 
4 scala> def g(y: Double) = 1 / y
5 g: (y: Double)Double

1 scala> def gof(x: Double) = g(f(x))
2 gof: (x: Double)Double
3 
4 scala> gof(2)
5 res42: Double = 0.25
6 
7 scala> gof(4)
8 res43: Double = 0.0625

 1 val lst = List(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
 2 lst.map(x => x * x)
 3 > res0: List[Int] = List(1, 4, 9, 16, 25, 36, 49, 64, 81, 100)
 4 
 5 lst.filter(x => x % 3 == 0)
 6 > res1: List[Int] = List(3, 6, 9)
 7 
 8 lst.reduce((x, y) => x + y)
 9 > res2: Int = 55
10 
11 lst.fold(0)((x, y) => x + y)
12 > res3: Int = 55

 1 lst.reduce((x, y) => x * y)
 2 > res4: Int = 3628800
 3 
 4 lst.fold(1)((x, y) => x * y)
 5 > res5: Int = 3628800
 6 
 7 lst.reduceLeft((x, y) => x * y)
 8 > res6: Int = 3628800
 9 
10 lst.foldLeft(1)((x, y) => x * y)
11 > res7: Int = 3628800
12 
13 lst.reduceRight((x, y) => x * y)
14 > res8: Int = 3628800
15 
16 lst.foldRight(1)((x, y) => x * y)
17 > res9: Int = 3628800

1 val result = (1 to 20)
2     .map(x => x * x)
3     .groupBy(_ % 5).par
4     .map { y => y._2.sum }
5     .sum
6 > result  : Int = 2870

 1 def add(a: Int, b: Int) = a + b
 2 > add: (a: Int, b: Int)Int
 3 val myfunc = (a: Int, b: Int) => a + b
 4 > myfunc  : (Int, Int) => Int = <function2>
 5 val otherfunc = add _
 6 > otherfunc  : (Int, Int) => Int = <function2>
 7 
 8 add(2, 4) // > res0: Int = 6
 9 myfunc(4, 5) // > res1: Int = 9
10 otherfunc(6, 7) // > res2: Int = 13
11 
12 (x: Int, y: Int, z: Int) => x * y * z
13 > res3: (Int, Int, Int) => Int = <function3>
14 
15 ((x: Int, y: Int, z: Int) => x * y * z)(5,4,3)
16 > res4: Int = 60

 1 scala> def transform(fn: (Int) => Int, number: Int) = fn(number)
 2 transform: (transformer: Int => Int, number: Int)Int
 3 
 4 scala> val plus5 = transform( (x: Int) => x + 5, _: Int)
 5 plus5: Int => Int = <function1>
 6 
 7 scala> val into3 = transform( (x: Int) => x * 3, _: Int)
 8 into3: Int => Int = <function1>
 9 
10 scala> plus5(6)
11 res6: Int = 11
12 
13 scala> into3(6)
14 res7: Int = 18

1 scala> def stat(num: List[Int]) = { (num.sum, num.sum/num.length.toDouble) }
2 stat: (num: List[Int])(Int, Double)
3 
4 scala> val list1 = List(1,2,3,4,5); val list2 = List(6,7,8,9,10)
5 list1: List[Int] = List(1, 2, 3, 4, 5)
6 list2: List[Int] = List(6, 7, 8, 9, 10)
7 
8 scala> (stat(list1), stat(list2))
9 res57: ((Int, Double), (Int, Double)) = ((15,3.0),(40,8.0))

1 scala> def factorial(n: Int): Int = { 
2            if(n=0) 1 
3            else n*factorial(n-1)
4        }
5 factorial: (n: Int)Int
6 
7 scala> factorial(5)
8 res2: Int = 120

1 scala> lazy val a = b + 1; lazy val b = 1;
2 a: Int = <lazy>
3 b: Int = <lazy>
4 
5 scala> a
6 res36: Int = 2
7 
8 scala> b
9 res37: Int = 1

 1 scala> def withinTx(block: () => Unit) = {
 2          println("Begin TX"); block() ; println("End TX")
 3        }
 4 withinTx: (block: () => Unit)Unit
 5 
 6 scala> withinTx { () => println("Performing operation") }
 7 Begin TX
 8 Performing operation
 9 End TX
10 
11 scala> def insideTx(block: => Unit) = {
12           println("Begin TX"); block ; println("End TX")
13        }
14 insideTx: (block: => Unit)Unit
15 
16 scala> insideTx { println("Performing operation") }
17 Begin TX
18 Performing operation
19 End TX

 1 trait Perishable {
 2     def name: String
 3     def lifespan: Int
 4 }
 5 
 6 class Person {
 7     // class body
 8     def age() = { 19 }
 9 }
10 
11 object TheCat {
12     // object body
13     def sayHelloNTimes(n: Int, name: String): String = { "" }
14 }

1 interface Animal {
2    public String name();
3    public int lifespan();
4 }

1 class Animal {
2   // class body
3   val age = 10
4   def method1(p1: Int, p2: String): String = {
5     /* some operations here */
6   }
7 }
8 
9 val a = new Animal // this is an instance of class Animal

1 object Animal {
2   // object body
3   val age = 10 // object member
4   def method1(p1: Int, p2: String): String = { /* some operations here */ }
5 }
6 
7 println(Animal.age)

 1 class Animal(name: String, lifespan: Int) {
 2   def makeNoise(volume: Int): String = { 
 3     name + " at volume: " + volume
 4   }
 5 }
 6 
 7 object Animal {
 8   def apply(name: String, lifespan: Int) = new Animal(name, lifespan)
 9 }
10 
11 val a0 = new Animal("Mammoth", 100)
12 val a1 = Animal("Elephant", 40)

1 def veryLoud(animal: { def makeNoise(vol: Int): String }) = {
2   animal.makeNoise(10)
3 }
4 
5 val a0 = new Animal("Mammoth", 100)
6 veryLoud(a0)

 1 package oop;
 2 import java.util.Arrays;
 3 public class MyEngines {
 4     enum FuelLevel {Empty, Reserve, Half, Full}
 5     interface Startable { public void start(); }
 6     interface Stoppable { public void stop(); }
 7 
 8     abstract class Engine implements Startable, Stoppable { ... }
 9     class TwoStrokeEngine extends Engine { ... }
10     class FourStrokeEngine extends Engine { ... }
11 
12     interface Make { ... }
13     class SteamEngine extends Engine implements Make { ... }
14 
15     public static void main() { ... }
16 }

 1 abstract class Engine implements Startable, Stoppable {
 2     int horsePower;
 3     FuelLevel fuelLevel;
 4     boolean running = false;
 5     public Engine(int hp, boolean state, FuelLevel fl) {
 6         this.horsePower = hp; this.running = state; this.fuelLevel = fl;
 7     }
 8     @Override
 9     public void start() {
10         switch (fuelLevel) {
11         case Empty:
12             System.out.println("Cannot start without fuel.");
13         default:
14             if (!running) {
15                 running = true;
16                 System.out.println("Engine started");
17             } else System.out.println("Engine already started");
18         }
19     }
20     @Override
21     public void stop() {
22         if (running) {
23             running = false; System.out.println("Engine stopped");
24         }
25     }
26     @Override
27     public String toString() {
28         return String.format(
29          "Engine(running: %s, fuelLevel: %s, horsePower: %d BHP)", running, fuelLevel, horsePower);
30     }
31 }

 1 class TwoStrokeEngine extends Engine {
 2     String model;
 3     public TwoStrokeEngine(int hp, boolean state, FuelLevel fl) {
 4         super(hp, state, fl);
 5     }
 6     @Override
 7     public String toString() {
 8         return "TwoStroke" + super.toString();
 9     }
10 }
11 
12 class FourStrokeEngine extends Engine {
13     String model;
14     public FourStrokeEngine(int hp, boolean state, FuelLevel fl) {
15         super(hp, state, fl);
16     }
17     @Override
18     public String toString() {
19         return "FourStroke" + super.toString();
20     }
21 }

 1 interface Make {
 2     public String make();
 3 }
 4 
 5 class SteamEngine extends Engine implements Make {
 6     String model = "IndianRailways";
 7     public SteamEngine(int hp, boolean state, FuelLevel fl) {
 8         super(hp, state, fl);
 9     }
10     public SteamEngine(int hp, boolean state, FuelLevel fl, String modelName) {
11         this(hp, state, fl);
12         this.model = modelName;
13     }
14     @Override
15     public String make() { return "SteamEngine - " + model; }
16     @Override
17     public String toString() {
18         return "Steam" + super.toString();
19     }
20 }

 1 public static void main(String[] args) {
 2 
 3     MyEngines me = new MyEngines();
 4 
 5     FourStrokeEngine e1 = me.new FourStrokeEngine(40, false,
 6             FuelLevel.Empty);
 7     System.out.println(e1);
 8     e1.start(); // won't start
 9     e1.fuelLevel = FuelLevel.Full;
10     e1.start(); // will start: fuel-tank is now full
11     System.out.println(e1 + "\n");
12 
13     TwoStrokeEngine e2 = me.new TwoStrokeEngine(26, false, FuelLevel.Full);
14     System.out.println(e2);
15     e2.start();
16     System.out.println(e2 + "\n");
17 
18     SteamEngine e3 = me.new SteamEngine(1800, true, FuelLevel.Reserve);
19     System.out.println(e3);
20     System.out.println(e3.make() + "\n");
21 
22     Engine[] myengines = { e1, e2, e3 };
23     System.out.println(Arrays.asList(myengines) + "\n");
24 }

 1 package oop
 2 object engine {
 3   object FuelLevel extends Enumeration {
 4     type FuelLevel = Value
 5     val Empty, Reserve, Half, Full = Value 
 6   }
 7   import FuelLevel._
 8 
 9   trait Stoppable {
10     var running: Boolean
11     var fuelLevel: FuelLevel
12     def stop = if (running) {running = false; println("Engine stopped")}
13   }
14 
15   trait Startable {
16     var running: Boolean
17     var fuelLevel: FuelLevel
18     def start = fuelLevel match {
19         case FuelLevel.Empty => println("Cannot start without fuel.")
20         case _ if ! running => {
21           running = true; println("Engine started")
22         }
23         case _ => println("Engine already running")
24       }
25   }

 1   class Engine(hp: Int, state: Boolean, fl: FuelLevel)
 2     extends Startable with Stoppable {
 3     val horsePower = hp
 4     var fuelLevel = fl
 5     var running = state
 6     override def toString="Engine(running: %s, fuelLevel: %s, horsePower: %dBHP)"
 7       .format(running, fuelLevel, horsePower)
 8   }
 9   class TwoStrokeEngine(hp: Int, state: Boolean, fl: FuelLevel)
10     extends Engine(hp, state, fl) {
11     override def toString = "TwoStroke" + super.toString()
12   }
13   class FourStrokeEngine(hp: Int, state: Boolean, fl: FuelLevel)
14     extends Engine(hp, state, fl) {
15     override def toString = "FourStroke" + super.toString()
16   }
17 
18   trait Make {def make: String}
19 
20   class SteamEngine(hp: Int, state: Boolean, fl: FuelLevel, modelName: String)
21     extends Engine(hp, state, fl) with Make {
22     private val model = modelName
23     def this(hp: Int, state: Boolean, fl: FuelLevel) = this(hp, state, fl, "Toy")
24     def make = "SteamEngine - " + model
25   }

 1   def main(args: Array[String]) {
 2     val e1 = new FourStrokeEngine(40, false, FuelLevel.Empty)
 3     println(e1)
 4     e1.start // won't start
 5     e1.fuelLevel = FuelLevel.Full
 6     e1.start // will start: fuel-tank is now full
 7     println(e1 + "\n")
 8 
 9     val e2 = new TwoStrokeEngine(40, false, FuelLevel.Full)
10     println(e2)
11     e2.start
12     println(e2 + "\n")
13 
14     val e3 = new SteamEngine(300, true, FuelLevel.Reserve)
15     println(e3)
16     println(e3.make + "\n")
17 
18     val myengines = Array(e1, e2, e3)
19     println(myengines + "\n")
20   }
21 }