Title: Partial Functions
Slug: partial_functions
Summary: Partial Functions Using Scala.
Date: 2017-01-03 12:00
Category: Scala
Tags: Basics
Authors: Chris Albon

If you want to learn more, check out Scala Cookbook and Programming in Scala.

isDefinedAt determines which inputs are accepted. apply is the actual operation.

Create A Partial Function



In [21]:

    
// Create a new partial function that inputs a integer and outputs a string
val dayOfTheWeek = new PartialFunction[Int, String] {
    // Create an array with the days of the week
    val days = Array("Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday", "Sunday")
    
    // Only accept input integers that are between 0 and 6
    def isDefinedAt(i: Int) = i > 0 && i < 6
    
    // If accepted, return the correct day of the week string
    def apply(i: Int) = days(i-1)
}

Run The Partial Function



In [22]:

    
dayOfTheWeek(2)









    Out[22]:





Tuesday