Lists

Lists are ordered, immutable collections of elements.

val numbers = List(1, 2, 3, 4, 5)
val names = List("Alice", "Bob", "Charlie")

Arrays

Arrays are ordered, mutable collections of elements.

val numbers = Array(1, 2, 3, 4, 5)
numbers(0) = 10 // Modifying an element

Sets

Sets are unordered collections of unique elements.

val uniqueNumbers = Set(1, 2, 3, 4, 5, 1, 2) // Set(5, 1, 2, 3, 4)

Maps

Maps are collections of key-value pairs.

val ages = Map("Alice" -> 30, "Bob" -> 25, "Charlie" -> 35)

Collection Operations

Scala provides a rich set of operations for working with collections.

Map

The map operation applies a function to each element in a collection and returns a new collection with the results.

val numbers = List(1, 2, 3)
val squaredNumbers = numbers.map(x => x * x) // List(1, 4, 9)

Filter

The filter operation selects elements from a collection that satisfy a given condition.

val numbers = List(1, 2, 3, 4, 5)
val evenNumbers = numbers.filter(x => x % 2 == 0) // List(2, 4)

Fold

The fold operation combines the elements of a collection into a single value.

val numbers = List(1, 2, 3, 4, 5)
val sum = numbers.fold(0)((x, y) => x + y) // 15

Reduce

The reduce operation is similar to fold, but it does not require an initial value.

val numbers = List(1, 2, 3, 4, 5)
val product = numbers.reduce((x, y) => x * y) // 120

Immutable vs. Mutable Collections

Scala distinguishes between immutable and mutable collections. Immutable collections cannot be modified after they are created, while mutable collections can.

Working with Sequences

Sequences are ordered