Scala Programming Examples

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scala

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

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scala

object HelloWorld {
    
    type Word = String
    type Occurrences = List[(Char, Int)]
    
    def wordOccurrences(w: Word): Occurrences = (w.toLowerCase().groupBy((element: Char) => element) map {
        case (k, v) => (k, v.length)
    }).toList
    
}

Compile and Execute Scala Online

scala

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

data

scala

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

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scala

object HelloWorld {
   def main(args: Array[String]) {
      println("Higher Order Functions Examples: ")
      
      // combining any arithmatic operation
      println(sum(1,2,5, (a,b)=>a+b))
      
      // or can be done by lambda expressions
      println(sum(3,5,9, _+_))
   }
   
   def sum(a: Int, b: Int, c: Int, f :(Int, Int) => Int): Int = f(f(a,b),c)
}

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scala

object HelloWorld {  // tail recursion optimisation, inak tiez Tail calls

  def add(a:Int, b: Int):Int = {  // klasicka rekurzivna funkcia
    if (a == 0) b;                // return nemusime pisat, sme vo funckionalnom svete, posledny vyraz je vystupna hodnota
    else add(a-1, b)+1;
  }
  def add1(a:Int, b: Int):Int = {  // iterativna verzia
    if (a == 0) b;
    else add1(a-1, b+1);          // po tomto volani sa nerobi nic, takze je to goto
  }
  def fib(n : Int) : Int = {      // sucin cisel 1.2. ... n
     if (n < 2) 1 
     else fib(n-2) + fib(n-1);
  }    
  def fact(n: Int): Int = {
      def fact(n: Int, acc: Int): Int =
         if (n <= 0) acc
         else fact(n-1, n*acc)
      fact(n, 1)
  }
  def sum(n: Int): Int = {      // sucet cisel 1+2+3+ ... +n
     @annotation.tailrec
     def sum(n: Int, acc: Int): Int =
        if (n <= 0) acc
        else sum(n-1, n+acc)    // akumulatorova technika
     sum(n, 0)
  }    
  def collatz(n : Int): Int = {  // vrati dlzku collatzovej postupnosti zacinajucej od n
    if (n == 1) 0
    else if (n % 2 == 0) 1+collatz(n/2)
    else 1+collatz(3*n+1)
  }
  def collatz1(n : Int): Int = {  // vrati dlzku collatzovej postupnosti zacinajucej od n
    @annotation.tailrec
    def collatz1(n : Int, count : Int): Int = {  // vrati dlzku collatzovej postupnosti zacinajucej od n
      if (n == 1) count
      else if (n % 2 == 0) collatz1(n/2, count+1)
      else collatz1(3*n+1, count+1)
    }
    collatz1(n, 0)
  }

  def main(args: Array[String]) {
     println(add(10000, 10000))  // toto padne na stacku
     // println(add(100000, 100000))  // toto padne na stacku
     val milion = 1000000000
     println(add1(milion , milion) + "=" + (2*milion))  // Gaussov vzorec)
     println("fibs=" + List.range(1, 20).map { fib })
     println("facts=" + List.range(1, 20).map { fact  })
     println("sums=" + List.range(1, 20).map { sum  })
     val stoLitrov = milion/10
     println(sum(stoLitrov) + "=" +  (stoLitrov*(stoLitrov+1)/2))  // Gaussov vzorec
     
     println(List.range(1,1000).map { n => collatz(n) })
     val desatLitrov = 10000
     //println(List.range(1,desatLitrov).map { n => collatz(n) }.max) // OutOfMemoryError: GC overhead limit exceeded
     // println(List.range(1,desatLitrov).map { n => collatz1(n) }.max)
     var max = -1
     for(i <- 1 to stoLitrov) {
       val len = collatz1(i)
       if (len > max)
         max = len
     }
     println(max)
    }
}

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scala

object HelloWorld {
  
  def addN(n: Int): Int => Int = (x: Int) => {
    x + n
  }

  def iteruj(n: Int, f: Int => Int): Int => Int = n match {
    case 0 => (x: Int) => x
    case _ => (x: Int) => iteruj(n - 1, f)(f(x))
  }

  def logaritmickyIteruj(n: Int, f: Int => Int): Int => Int = n match {
    case 0 => (x: Int) => x
    case _ => if (n % 2 == 0) (x: Int) => iteruj(n / 2, f)(iteruj(n / 2, f)(x)) else (x: Int) => iteruj(n - 1, f)(f(x))
  }

  type realnaFunkcia = Double => Double

  def kompozicia(f: realnaFunkcia, g: realnaFunkcia): realnaFunkcia = {
    (x: Double) => f(g(x))
  }

  def iteracia(n: Int, f: realnaFunkcia): realnaFunkcia = n match {
    case 0 => (x: Double) => x
    case _ => kompozicia(f, iteracia(n - 1, f))
  }
  
  def main(args: Array[String]): Unit = {
    println(iteruj(10,addN(5))(4))
    println(iteruj(10,addN(10))(4))
  }  
}

Compile and Execute Scala Online

scala

object HelloWorld {
  
  def addN(n: Int): Int => Int = (x: Int) => {
    x + n
  }

  def iteruj(n: Int, f: Int => Int): Int => Int = n match {
    case 0 => (x: Int) => x
    case _ => (x: Int) => iteruj(n - 1, f)(f(x))
  }

  def logaritmickyIteruj(n: Int, f: Int => Int): Int => Int = n match {
    case 0 => (x: Int) => x
    case _ => if (n % 2 == 0) (x: Int) => iteruj(n / 2, f)(iteruj(n / 2, f)(x)) else (x: Int) => iteruj(n - 1, f)(f(x))
  }

  type realnaFunkcia = Double => Double

  def kompozicia(f: realnaFunkcia, g: realnaFunkcia): realnaFunkcia = {
    (x: Double) => f(g(x))
  }

  def iteracia(n: Int, f: realnaFunkcia): realnaFunkcia = n match {
    case 0 => (x: Double) => x
    case _ => kompozicia(f, iteracia(n - 1, f))
  }
  
  def main(args: Array[String]): Unit = {
    println(iteruj(10,addN(5))(4))
    println(iteruj(10,addN(10))(4))
  }  
}

Compile and Execute Scala Online

scala

import scala.collection.mutable.ArrayBuffer
import scala.collection.mutable.ListBuffer
object HelloWorld {
   def main(args: Array[String]) {
      val rdd = "c71amt"
      val parsed = rdd.replaceAll("[0-9$&+,:;=?@#|'<>.-^*()%!]","")
      val dictionary = List("camt", "tamc", "mact", "cmat", "catm")
      val list = parsed.toList
      var count = list.length*(list.length-1).toInt
      var ab = new ListBuffer[String]()
      var printer = new ListBuffer[String]()
      while(count > 0){
           var random = scala.util.Random.shuffle(list)
           var wordtomatch = random.mkString
           ab += wordtomatch
           ab = ab.distinct
            if(dictionary.contains(wordtomatch) == true){
                printer += wordtomatch
                count=count-1;
            }
            }
        printer = printer.distinct
        printer.foreach(println)
       }
}

beutlfulbjksd

scala

object Demo {
   def main(args: Array[String]) {
      var a = 10;
      
      // An infinite loop.
      while( true ){
         println( "Value of a: " + a );
      }
   }
}

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