: In Scala, functions are first-class citizens. You can pass them as arguments to other functions (like map , filter , or flatmap ) or return them as values.
Consider a simple task: buying a coffee. In a standard imperative style, you might have a side effect where the credit card is charged immediately. In a functional style, you return the charge as a to be processed later. Impure Code (Side Effect):
: Think of this as "switch statements on steroids." It allows you to deconstruct data structures like Case Classes or Options with type safety. Functional Programming in Scala
: Once a value is created, it never changes. Instead of modifying a list, you create a new one with the desired changes. This eliminates entire classes of bugs related to shared mutable state.
To write functional Scala, you need to master three fundamental concepts: : In Scala, functions are first-class citizens
: A function is "pure" if it always returns the same output for the same input and has no side effects (like printing to a console or updating a database).
def buyCoffee(cc: CreditCard): Coffee = val cup = new Coffee() cc.charge(cup.price) // Side effect: hits the bank API immediately cup Use code with caution. Copied to clipboard Learning Functional Programming with Scala | by Ryan Susana In a standard imperative style, you might have
: Say goodbye to NullPointerException . The Option[T] container forces you to explicitly handle cases where a value might be missing ( Some(value) or None ). 3. Practical Example: From Impure to Pure