Datastructures in Scala

DataStructureExample.scala

package learn.scala

/**
	* Datastructures in Scala
	* The example below shows abstracting Rational numbers and implementing
	* rational number arithmetics.
	*
	* Similar to java scala does provide toString for printing the datastructure representation.
	* In the example below we override toString method. Also, we make use of this construct which
	* is also available in Scala.
	* Introduction to the access modifiers here GCD for example
	* pre checks using require function
	*/
class Rational(x: Int, y: Int) {
  // represents a check on denominator
  require(y != 0, "Denominator must be a non zero")
  
  // private GCD definition abstracted from client
  private def gcd(x: Int, y: Int): Int = if (y==0) x else gcd(y, x % y)
  
  // another constructor other than default expressed in the definition to support integers
  // all integers are rational with denominator as 1
  def this(x: Int) = this(x, 1)
  
  def numerator = x
  def denominator = y
  
  def sum ( rational: Rational): Rational = {
  	val newNumer = (this.numerator * rational.denominator) + (this.denominator * rational.numerator)
  	val newDenom = this.denominator * rational.denominator
  	val result = new Rational(newNumer, newDenom)
  	result
  }
  
  def less(that: Rational): Boolean = this.numerator * that.denominator < that.numerator * this.denominator
  
  override def toString = 	(this.numerator / gcd(this.numerator, this.denominator)) + "/" + (this.denominator / gcd(this.numerator, this.denominator))
}

object DataStructureExample {
	val rational = new Rational (1, 2)        //> rational  : learn.scala.Rational = 1/2
	rational.numerator                        //> res0: Int = 1
	rational.denominator                      //> res1: Int = 2
	
	// ---------------- adding two rational number ------------------
	val rational1 = new Rational(5,6)         //> rational1  : learn.scala.Rational = 5/6
	val rational2 = rational.sum(rational1)   //> rational2  : learn.scala.Rational = 4/3
	
	rational2.numerator                       //> res2: Int = 16
	rational2.denominator                     //> res3: Int = 12
	
	rational1.less(rational2)                 //> res4: Boolean = true
	println(rational2)                        //> 4/3
}