Immutability | Functional Programming In Scala

What is Immutability?

Immutability is a concept in programming where an object cannot be modified after it has been created. In Scala, immutability is a fundamental principle that promotes safer and more predictable code. When an object is immutable, any modification results in the creation of a new object rather than altering the original one.

Why Use Immutability?

Immutability offers several benefits:

Thread Safety: Immutable objects can be safely shared between threads without synchronization.
Predictability: When objects do not change, your code becomes easier to reason about.
Functional Programming: Immutability is a core concept in functional programming, allowing for the use of functions as first-class citizens.
Ease of Debugging: Since the state of immutable objects does not change, you can easily track the flow of data in your application.

Immutability in Scala

In Scala, you can create immutable objects using the val keyword. This keyword signifies that a variable cannot be reassigned. For example:

Example:

val number = 10

This creates an immutable variable number with a value of 10. If you try to reassign it, you will get an error.

Here's what happens when you try to reassign an immutable variable:

Example:

number = 20

Error: reassignment to val number

Immutable Collections

Scala provides several immutable collection types, including List, Set, and Map. These collections cannot be changed after they are created. For example:

Example:

val fruits = List("Apple", "Banana", "Cherry")

You can perform operations that return a new collection without altering the original:

val moreFruits = fruits :+ "Date"

The fruits list remains unchanged, while moreFruits contains the new item.

Creating New Instances

When working with immutable objects, rather than modifying an existing object, you create a new instance with the desired changes. Consider a case class in Scala:

Example:

case class Person(name: String, age: Int)

To change a person's age, you create a new instance:

val person1 = Person("Alice", 30)

val person2 = person1.copy(age = 31)

This keeps person1 unchanged while creating person2 with the updated age.

Conclusion

Immutability is a powerful concept in Scala, promoting safer and clearer code. By embracing immutability, you can leverage the benefits of functional programming, enhance thread safety, and simplify debugging. Understanding how to work with immutable variables and collections is essential for any Scala developer.