Learn the syntax, data types, and operations essential for programming in Scala

Become a Scala Developer

In this module, we will learn Scala from the ground up. This module aims to teach us how to write basic programs, assuming we have no prior knowledge of the language. We will start with a brief introduction to Scala to understand its functionality and applications. We will then move discuss the key features and functions of the language (data types, functions, classes, etc.) in detail. In the end, we will have all the basic knowledge of how to program in Scala.

Learn Scala from Scratch

Let's look at an example where we will learn how to implement higher-order functions and also understand the type of scenarios in which they should be used. 

Below, we are going to define a set of recursive functions which all perform some sort of summation.

def sumOfInts(a: Int, b: Int): Int ={
  if(a>b) 0
  else a + sumOfInts(a+1,b)
}

println(sumOfInts(1,5))

Docker

# 2. Sum of the cubes of all the integers between ‘a’ and ‘b’

def cube(x: Int): Int ={
  x * x * x
}

def sumOfCubes(a: Int, b: Int): Int ={
  if(a>b) 0
  else cube(a) + sumOfCubes(a+1,b)
}

println(sumOfCubes(1,5))

# 3. Sum of the factorials of all the integers between ‘a’ and ‘b’

def factorial(x: Int): Int = {
  if(x==0) 1
  else x * factorial(x-1)
}

def sumOfFactorials(a: Int, b: Int): Int ={
  if(a>b) 0
  else factorial(a) + sumOfFactorials(a+1,b)
}

println(sumOfFactorials(1,5))

You might have noticed that all the functions we have defined above are different cases of: 
$$ \sum_{n=a}^b f(n)$$

With $f$ being any of the functions above.

Can we factor out the common pattern into a single function rather than have three separate functions?

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In the next lesson, we will try to solve the above problem using higher-order functions.

In this lesson, we will write a summation program using the methods we have learned so far.

Learning by Example: Summation