Lesson 2: Scala Programming Language Tutorial

Lesson 2: Scala Programming Language Tutorial

Here are four Scala code examples, each with four explanation points, repeating the relevant code fragment inside each point.

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Example 1: Conditional Statements (if-else)

val number = 10

if (number > 0) {
  println("Positive number")
} else {
  println("Negative number")
}

Explanation:

1. val number = 10 – Declares an immutable variable number and assigns it the value 10.

2. if (number > 0) { – Checks if number is greater than 0, executing the block inside if true.

3. println("Positive number") – If number > 0, prints "Positive number".

4. else { println("Negative number") } – If number is not greater than 0, prints "Negative number".

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Example 2: Pattern Matching (match)

val day = 3

val result = day match {
  case 1 => "Monday"
  case 2 => "Tuesday"
  case 3 => "Wednesday"
  case _ => "Unknown"
}
println(result)

Explanation:

1. val day = 3 – Declares a variable day with value 3.

2. val result = day match { – Uses pattern matching to assign a value based on day.

3. case 3 => "Wednesday" – When day is 3, assigns "Wednesday" to result.

4. case _ => "Unknown" – The wildcard _ handles unmatched cases, assigning "Unknown".

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Example 3: Lists and Iteration

val numbers = List(1, 2, 3, 4, 5)

for (num <- numbers) {
  println(s"Number: $num")
}

Explanation:

1. val numbers = List(1, 2, 3, 4, 5) – Creates a list of numbers from 1 to 5.

2. for (num <- numbers) { – Iterates over each element in numbers.

3. println(s"Number: $num") – Prints "Number: X" where X is the list element.

4. } – Ends the loop after processing all elements in numbers.

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Example 4: Higher-Order Functions (map)

val numbers = List(1, 2, 3)
val doubled = numbers.map(x => x * 2)
println(doubled)

Explanation:

1. val numbers = List(1, 2, 3) – Defines a list containing 1, 2, 3.

2. val doubled = numbers.map(x => x * 2) – Applies a function that doubles each element.

3. x => x * 2 – Anonymous function that multiplies each x by 2.

4. println(doubled) – Prints List(2, 4, 6), the transformed list.

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This is Lesson 2 of Scala programming covering conditions, pattern matching, loops, and higher-order functions.