Scala Functions and Data

rational.scala

class Rational(x: Int, y: Int) {

  require(y != 0, "denominator must be non zero")

  def this(x: Int) = this(x, 1)

  private def gcd(a: Int, b: Int): Int = if (b == 0) a else gcd(b, a % b)

  private val g = gcd(x, y)

  def numer = x / g

  def denom = y / g

  def unary_- : Rational = new Rational(-numer, denom)

  def +(that: Rational): Rational = {
    new Rational(numer * that.denom + that.numer * denom, denom * that.denom)
  }

  def -(that: Rational): Rational = this + -that

  def <(that: Rational) = numer * that.denom < that.numer * denom

  def max(that: Rational) = if (this < that) that else this

  override def toString = numer + "/" + denom
}

val rational1 = new Rational(1, 3)
val rational2 = new Rational(5, 7)
val rational3 = new Rational(3, 2)
val rational4 = new Rational(3)

rational1 - rational2 - rational3
rational2 + rational2
rational1 < rational2
rational1 max rational2
-rational4