Funcional Programming in Scala - Chapter 4

Funcional Programming in Scala - Chapter 4

• 1.
  HANDLING ERRORS WITHOUTEXCEPTIONS FUNCTIONAL PROGRAMMING IN SCALA
• 2.
  SIDE EFFECT
• 3.
  CHAPTER 4 MAIN PROBLEMSWITH EXCEPTIONS ▸ Context dependence ▸ Exceptions are not type-safe ▸ Checked exceptions def map[A,B](l: List[A])(f: A => B): List[B]
• 4.
  CHAPTER 4 EXAMPLE // partialfunction
 def mean(xs: Seq[Double]): Double =
 if (xs.isEmpty)
 throw new ArithmeticException("mean of empty list!")
 else xs.sum / xs.length
 
 def mean1(xs: Seq[Double]): Double =
 if (xs.isEmpty)
 null
 else xs.sum / xs.length
• 5.
  CHAPTER 4 EXAMPLE // totalfunction
 def mean_1(xs: Seq[Double], onEmpty: Double): Double =
 if (xs.isEmpty) 
 onEmpty
 else 
 xs.sum / xs.length
• 6.
  CHAPTER 4 OPTION sealed traitOption[+A]
 
 case class Some[+A](get: A) extends Option[A]
 
 case object None extends Option[Nothing]
• 7.
  CHAPTER 4 HOW TOUSE OPTION TYPE CORRECTLY ▸ Reference Option example
• 8.
  CHAPTER 4 STRUCTURAL RECURSION ▸map ▸ flatMap
• 9.
  CHAPTER 4 MONAD trait M[A] {   def flatMap[B](f: A => M[B]): M[B] } def unit[A](x: A): M[A]
• 10.
  CHAPTER 4 REFERENCE ▸ MonadDesign Pattern in Java ▸ Demystifying the Monad in Scala