15 Anonymous functions

 

After reading this lesson, you will be able to

  • Implement anonymous functions
  • Code using the concise notation for anonymous functions

In lesson 6, you learned the basics of functions in Scala. In this lesson, you’ll discover a new type of function: anonymous. Anonymous functions are functions that you can define quickly and concisely. At first, they may seem just an alternative to the standard Scala functions you have seen so far, but you’ll soon discover that they are particularly handy when combined with another type of function called higher order. The concept of an anonymous function is not unique to Scala; other languages, such as Java 8+ and Python, refer to it as lambda. In the capstone, you will use a particular kind of anonymous function called partial to define your HTTP server’s routes.

Consider this

Consider the following two functions to sum and subtract two integers:

def sum(a: Int, b: Int): Int = a + b 
 
    def subtract(a: Int, b: Int): Int = a - b

Which parts do these two functions have in common? How are they different? Can you think of a more concise way of achieving the same implementation?

15.1 Function vs. anonymous function

Suppose you implemented a calculator program to perform the standard operations on integers (i.e., sum, subtraction, multiplication, division) together with negation.

15.2 Concise notation for anonymous functions

Summary

Answers to quick checks